diff --git a/.eslintrc.yml b/.eslintrc.yml
index b7a6b8990e..09d5dc145a 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -8,7 +8,9 @@
     '@typescript-eslint/lines-between-class-members':
       - error
       - exceptAfterSingleLine: true
+    '@typescript-eslint/naming-convention': off # TODO: reenable
     '@typescript-eslint/no-unused-vars': off # TODO: reenable
+    '@typescript-eslint/no-unused-expressions': off # TODO: reenable
     '@typescript-eslint/no-use-before-define':
       - error
       - variables: true
@@ -20,6 +22,7 @@
     class-methods-use-this:
       - off
     default-case: off
+    function-paren-newline: off # TODO: really tripping up. REENABLE
     guard-for-in: off # TODO: reenable
     import/no-cycle: off # TODO: reenable. disabled because circular deps are hard to fix right now
     import/prefer-default-export: off # named exports much better for .d.ts files
@@ -49,6 +52,8 @@
           multiline: true
     operator-linebreak: off # prevents JSX if statements looking correct. REVISIT for other uses
     prefer-const: off # TODO: revisit
+    prefer-destructuring: off # is too aggressive, sometimes doesn't make sense
+    prefer-template: off
     react/destructuring-assignment: off
     react/jsx-props-no-spreading: off # more acceptable in preact, b/c no proptype filtering
     react/react-in-jsx-scope: off # because we use preact
diff --git a/packages/common/src/CalendarContent.tsx b/packages/common/src/CalendarContent.tsx
index 3cba89d935..be387e06b5 100644
--- a/packages/common/src/CalendarContent.tsx
+++ b/packages/common/src/CalendarContent.tsx
@@ -24,7 +24,7 @@ import { EventClicking } from './interactions/EventClicking'
 import { EventHovering } from './interactions/EventHovering'
 import { getNow } from './reducers/current-date'
 import { CalendarInteraction } from './calendar-utils'
-import { DelayedRunner } from './util/runner'
+import { DelayedRunner } from './util/DelayedRunner'
 import { PureComponent } from './vdom-util'
 
 export interface CalendarContentProps extends CalendarData {
diff --git a/packages/common/src/common/render-hook.tsx b/packages/common/src/common/render-hook.tsx
index 6c6112c500..4bff07f107 100644
--- a/packages/common/src/common/render-hook.tsx
+++ b/packages/common/src/common/render-hook.tsx
@@ -218,7 +218,7 @@ export function buildClassNameNormalizer<HookProps>() { // TODO: general deep-me
   let currentHookProps: HookProps
   let currentClassNames: string[] = []
 
-  return function (generator: ClassNamesGenerator<HookProps>, hookProps: HookProps) {
+  return (generator: ClassNamesGenerator<HookProps>, hookProps: HookProps) => {
     if (!currentHookProps || !isPropsEqual(currentHookProps, hookProps) || generator !== currentGenerator) {
       currentGenerator = generator
       currentHookProps = hookProps
diff --git a/packages/common/src/component/event-splitting.ts b/packages/common/src/component/event-splitting.ts
index 91c2b2a651..f2c4ed0c67 100644
--- a/packages/common/src/component/event-splitting.ts
+++ b/packages/common/src/component/event-splitting.ts
@@ -139,7 +139,7 @@ export abstract class Splitter<PropsType extends SplittableProps = SplittablePro
       let mutatedKeysByDefId = this._getKeysForEventDefs(interaction.mutatedEvents)
       let mutatedStores = this._splitEventStore(interaction.mutatedEvents, mutatedKeysByDefId)
 
-      let populate = function (key) {
+      let populate = (key) => {
         if (!splitStates[key]) {
           splitStates[key] = {
             affectedEvents: affectedStores[key] || EMPTY_EVENT_STORE,
diff --git a/packages/common/src/datelib/DateFormatter.ts b/packages/common/src/datelib/DateFormatter.ts
index aa21dde685..14599fea2b 100644
--- a/packages/common/src/datelib/DateFormatter.ts
+++ b/packages/common/src/datelib/DateFormatter.ts
@@ -12,7 +12,12 @@ export interface VerboseFormattingArg { // TODO: kill this
   defaultSeparator: string
 }
 
-export function createVerboseFormattingArg(start: ZonedMarker, end: ZonedMarker, context: DateFormattingContext, betterDefaultSeparator?: string): VerboseFormattingArg {
+export function createVerboseFormattingArg(
+  start: ZonedMarker,
+  end: ZonedMarker,
+  context: DateFormattingContext,
+  betterDefaultSeparator?: string,
+): VerboseFormattingArg {
   let startInfo = expandZonedMarker(start, context.calendarSystem)
   let endInfo = end ? expandZonedMarker(end, context.calendarSystem) : null
 
diff --git a/packages/common/src/datelib/formatting-native.ts b/packages/common/src/datelib/formatting-native.ts
index 7ec2a15984..de55b04c69 100644
--- a/packages/common/src/datelib/formatting-native.ts
+++ b/packages/common/src/datelib/formatting-native.ts
@@ -181,7 +181,7 @@ function buildNativeFormattingFunc(
     zeroFormat = new Intl.DateTimeFormat(context.locale.codes, zeroProps)
   }
 
-  return function (date: ZonedMarker) {
+  return (date: ZonedMarker) => {
     let { marker } = date
     let format
 
diff --git a/packages/common/src/interactions/interaction.ts b/packages/common/src/interactions/interaction.ts
index 5341ad3479..b1a16adf5f 100644
--- a/packages/common/src/interactions/interaction.ts
+++ b/packages/common/src/interactions/interaction.ts
@@ -42,4 +42,4 @@ export function interactionSettingsToStore(settings: InteractionSettings) {
 }
 
 // global state
-export let interactionSettingsStore: InteractionSettingsStore = {}
+export const interactionSettingsStore: InteractionSettingsStore = {}
diff --git a/packages/common/src/main.ts b/packages/common/src/main.ts
index 61ddd5e959..4c3f0ccfa0 100644
--- a/packages/common/src/main.ts
+++ b/packages/common/src/main.ts
@@ -218,9 +218,15 @@ export { requestJson } from './util/requestJson'
 
 export * from './vdom'
 export { BaseComponent, setRef } from './vdom-util'
-export { DelayedRunner } from './util/runner'
+export { DelayedRunner } from './util/DelayedRunner'
 
-export { ScrollGridProps, ScrollGridSectionConfig, ColGroupConfig, ScrollGridImpl, ScrollGridChunkConfig } from './scrollgrid/ScrollGridImpl'
+export {
+  ScrollGridProps,
+  ScrollGridSectionConfig,
+  ColGroupConfig,
+  ScrollGridImpl,
+  ScrollGridChunkConfig,
+} from './scrollgrid/ScrollGridImpl'
 export { SimpleScrollGrid, SimpleScrollGridSection } from './scrollgrid/SimpleScrollGrid'
 export {
   CssDimValue, ScrollerLike, SectionConfig, ColProps, ChunkConfig, hasShrinkWidth, renderMicroColGroup,
diff --git a/packages/common/src/options.ts b/packages/common/src/options.ts
index 2d5bd5f3a9..2ee7d565b8 100644
--- a/packages/common/src/options.ts
+++ b/packages/common/src/options.ts
@@ -402,7 +402,13 @@ export function mergeRawOptions(optionSets: Dictionary[]) {
   return mergeProps(optionSets, COMPLEX_OPTION_COMPARATORS)
 }
 
-export function refineProps<Refiners extends GenericRefiners, Raw extends RawOptionsFromRefiners<Refiners>>(input: Raw, refiners: Refiners): { refined: RefinedOptionsFromRefiners<Refiners>, extra: Dictionary } {
+export function refineProps<Refiners extends GenericRefiners, Raw extends RawOptionsFromRefiners<Refiners>>(
+  input: Raw,
+  refiners: Refiners,
+): {
+  refined: RefinedOptionsFromRefiners<Refiners>,
+  extra: Dictionary,
+} {
   let refined = {} as any
   let extra = {} as any
 
diff --git a/packages/common/src/plugin-system.ts b/packages/common/src/plugin-system.ts
index b5f0201e1d..6a5f87feae 100644
--- a/packages/common/src/plugin-system.ts
+++ b/packages/common/src/plugin-system.ts
@@ -106,7 +106,7 @@ export function buildBuildPluginHooks() { // memoizes
   let currentGlobalDefs: PluginDef[] = []
   let currentHooks: PluginHooks
 
-  return function (overrideDefs: PluginDef[], globalDefs: PluginDef[]) {
+  return (overrideDefs: PluginDef[], globalDefs: PluginDef[]) => {
     if (!currentHooks || !isArraysEqual(overrideDefs, currentOverrideDefs) || !isArraysEqual(globalDefs, currentGlobalDefs)) {
       currentHooks = buildPluginHooks(overrideDefs, globalDefs)
     }
diff --git a/packages/common/src/reducers/CalendarDataManager.ts b/packages/common/src/reducers/CalendarDataManager.ts
index 76d8f5a8fa..a0684b44a5 100644
--- a/packages/common/src/reducers/CalendarDataManager.ts
+++ b/packages/common/src/reducers/CalendarDataManager.ts
@@ -40,7 +40,7 @@ import { globalPlugins } from '../global-plugins'
 import { createEmptyEventStore } from '../structs/event-store'
 import { CalendarContext } from '../CalendarContext'
 import { CalendarDataManagerState, CalendarOptionsData, CalendarCurrentViewData, CalendarData } from './data-types'
-import { TaskRunner } from '../util/runner'
+import { TaskRunner } from '../util/TaskRunner'
 import { buildTitle } from './title-formatting'
 
 export interface CalendarDataManagerProps {
@@ -340,7 +340,11 @@ export class CalendarDataManager {
     }
   }
 
-  _computeOptionsData(optionOverrides: CalendarOptions, dynamicOptionOverrides: CalendarOptions, calendarApi: CalendarApi): CalendarOptionsData {
+  _computeOptionsData(
+    optionOverrides: CalendarOptions,
+    dynamicOptionOverrides: CalendarOptions,
+    calendarApi: CalendarApi,
+  ): CalendarOptionsData {
     // TODO: blacklist options that are handled by optionChangeHandlers
 
     let {
@@ -411,7 +415,11 @@ export class CalendarDataManager {
       if (optionName !== 'plugins') { // because plugins is special-cased
         if (
           raw[optionName] === currentRaw[optionName] ||
-          (COMPLEX_OPTION_COMPARATORS[optionName] && (optionName in currentRaw) && COMPLEX_OPTION_COMPARATORS[optionName](currentRaw[optionName], raw[optionName]))
+          (
+            COMPLEX_OPTION_COMPARATORS[optionName] &&
+            (optionName in currentRaw) &&
+            COMPLEX_OPTION_COMPARATORS[optionName](currentRaw[optionName], raw[optionName])
+          )
         ) {
           refined[optionName] = currentRefined[optionName]
         } else if (refiners[optionName]) {
@@ -438,7 +446,12 @@ export class CalendarDataManager {
     }
   }
 
-  _computeCurrentViewData(viewType: string, optionsData: CalendarOptionsData, optionOverrides: CalendarOptions, dynamicOptionOverrides: CalendarOptions): CalendarCurrentViewData {
+  _computeCurrentViewData(
+    viewType: string,
+    optionsData: CalendarOptionsData,
+    optionOverrides: CalendarOptions,
+    dynamicOptionOverrides: CalendarOptions,
+  ): CalendarCurrentViewData {
     let viewSpec = optionsData.viewSpecs[viewType]
 
     if (!viewSpec) {
@@ -482,7 +495,13 @@ export class CalendarDataManager {
     return { viewSpec, options: refinedOptions, dateProfileGenerator, viewApi }
   }
 
-  processRawViewOptions(viewSpec: ViewSpec, pluginHooks: PluginHooks, localeDefaults: CalendarOptions, optionOverrides: CalendarOptions, dynamicOptionOverrides: CalendarOptions) {
+  processRawViewOptions(
+    viewSpec: ViewSpec,
+    pluginHooks: PluginHooks,
+    localeDefaults: CalendarOptions,
+    optionOverrides: CalendarOptions,
+    dynamicOptionOverrides: CalendarOptions,
+  ) {
     let raw = mergeRawOptions([
       BASE_OPTION_DEFAULTS,
       viewSpec.optionDefaults,
@@ -599,40 +618,43 @@ function buildViewUiProps(calendarContext: CalendarContext) {
   let { options } = calendarContext
 
   return {
-    eventUiSingleBase: createEventUi({
-      display: options.eventDisplay,
-      editable: options.editable, // without "event" at start
-      startEditable: options.eventStartEditable,
-      durationEditable: options.eventDurationEditable,
-      constraint: options.eventConstraint,
-      overlap: typeof options.eventOverlap === 'boolean' ? options.eventOverlap : undefined,
-      allow: options.eventAllow,
-      backgroundColor: options.eventBackgroundColor,
-      borderColor: options.eventBorderColor,
-      textColor: options.eventTextColor,
-      color: options.eventColor
-      // classNames: options.eventClassNames // render hook will handle this
-    }, calendarContext),
-
-    selectionConfig: createEventUi({
-      constraint: options.selectConstraint,
-      overlap: typeof options.selectOverlap === 'boolean' ? options.selectOverlap : undefined,
-      allow: options.selectAllow
-    }, calendarContext)
+    eventUiSingleBase: createEventUi(
+      {
+        display: options.eventDisplay,
+        editable: options.editable, // without "event" at start
+        startEditable: options.eventStartEditable,
+        durationEditable: options.eventDurationEditable,
+        constraint: options.eventConstraint,
+        overlap: typeof options.eventOverlap === 'boolean' ? options.eventOverlap : undefined,
+        allow: options.eventAllow,
+        backgroundColor: options.eventBackgroundColor,
+        borderColor: options.eventBorderColor,
+        textColor: options.eventTextColor,
+        color: options.eventColor,
+        // classNames: options.eventClassNames // render hook will handle this
+      },
+      calendarContext,
+    ),
+    selectionConfig: createEventUi(
+      {
+        constraint: options.selectConstraint,
+        overlap: typeof options.selectOverlap === 'boolean' ? options.selectOverlap : undefined,
+        allow: options.selectAllow,
+      },
+      calendarContext,
+    ),
   }
 }
 
-
 function parseContextBusinessHours(calendarContext: CalendarContext) {
   return parseBusinessHours(calendarContext.options.businessHours, calendarContext)
 }
 
-
 function warnUnknownOptions(options: any, viewName?: string) {
   for (let optionName in options) {
     console.warn(
       `Unknown option '${optionName}'` +
-      (viewName ? ` for view '${viewName}'` : '')
+      (viewName ? ` for view '${viewName}'` : ''),
     )
   }
 }
diff --git a/packages/common/src/reducers/eventStore.ts b/packages/common/src/reducers/eventStore.ts
index 42c8572867..90a91725a0 100644
--- a/packages/common/src/reducers/eventStore.ts
+++ b/packages/common/src/reducers/eventStore.ts
@@ -18,7 +18,13 @@ import { DateEnv } from '../datelib/env'
 import { CalendarContext } from '../CalendarContext'
 import { expandRecurring } from '../structs/recurring-event'
 
-export function reduceEventStore(eventStore: EventStore, action: Action, eventSources: EventSourceHash, dateProfile: DateProfile, context: CalendarContext): EventStore {
+export function reduceEventStore(
+  eventStore: EventStore,
+  action: Action,
+  eventSources: EventSourceHash,
+  dateProfile: DateProfile,
+  context: CalendarContext,
+): EventStore {
   switch (action.type) {
     case 'RECEIVE_EVENTS': // raw
       return receiveRawEvents(
@@ -57,9 +63,9 @@ export function reduceEventStore(eventStore: EventStore, action: Action, eventSo
       return excludeEventsBySourceId(eventStore, action.sourceId)
 
     case 'REMOVE_ALL_EVENT_SOURCES':
-      return filterEventStoreDefs(eventStore, function(eventDef: EventDef) {
-        return !eventDef.sourceId // only keep events with no source id
-      })
+      return filterEventStoreDefs(eventStore, (eventDef: EventDef) => (
+       !eventDef.sourceId // only keep events with no source id
+      ))
 
     case 'REMOVE_ALL_EVENTS':
       return createEmptyEventStore()
diff --git a/packages/common/src/reducers/view-type.ts b/packages/common/src/reducers/view-type.ts
index 3477a4ab52..03ffd0da18 100644
--- a/packages/common/src/reducers/view-type.ts
+++ b/packages/common/src/reducers/view-type.ts
@@ -3,7 +3,7 @@ import { Action } from './Action'
 export function reduceViewType(viewType: string, action: Action): string {
   switch (action.type) {
     case 'CHANGE_VIEW_TYPE':
-      return viewType = action.viewType
+      viewType = action.viewType
   }
 
   return viewType
diff --git a/packages/common/src/scrollgrid/SimpleScrollGrid.tsx b/packages/common/src/scrollgrid/SimpleScrollGrid.tsx
index 58f7d46cc9..8c58ed7d0a 100644
--- a/packages/common/src/scrollgrid/SimpleScrollGrid.tsx
+++ b/packages/common/src/scrollgrid/SimpleScrollGrid.tsx
@@ -33,7 +33,10 @@ interface SimpleScrollGridState {
 
 export class SimpleScrollGrid extends BaseComponent<SimpleScrollGridProps, SimpleScrollGridState> {
   processCols = memoize((a) => a, isColPropsEqual) // so we get same `cols` props every time
-  renderMicroColGroup: typeof renderMicroColGroup = memoize(renderMicroColGroup) // yucky to memoize VNodes, but much more efficient for consumers
+
+  // yucky to memoize VNodes, but much more efficient for consumers
+  renderMicroColGroup: typeof renderMicroColGroup = memoize(renderMicroColGroup)
+
   scrollerRefs = new RefMap<Scroller>()
   scrollerElRefs = new RefMap<HTMLElement>(this._handleScrollerEl.bind(this))
 
diff --git a/packages/common/src/structs/event-parse.ts b/packages/common/src/structs/event-parse.ts
index aad01d349a..de8b9963be 100644
--- a/packages/common/src/structs/event-parse.ts
+++ b/packages/common/src/structs/event-parse.ts
@@ -71,7 +71,14 @@ export function parseEvent(
   )
 
   if (recurringRes) {
-    let def = parseEventDef(refined, extra, eventSource ? eventSource.sourceId : '', recurringRes.allDay, Boolean(recurringRes.duration), context)
+    let def = parseEventDef(
+      refined,
+      extra,
+      eventSource ? eventSource.sourceId : '',
+      recurringRes.allDay,
+      Boolean(recurringRes.duration),
+      context,
+    )
 
     def.recurringDef = { // don't want all the props from recurringRes. TODO: more efficient way to do this
       typeId: recurringRes.typeId,
@@ -105,7 +112,14 @@ export function buildEventRefiners(context: CalendarContext) {
 Will NOT populate extendedProps with the leftover properties.
 Will NOT populate date-related props.
 */
-export function parseEventDef(refined: EventRefined, extra: Dictionary, sourceId: string, allDay: boolean, hasEnd: boolean, context: CalendarContext): EventDef {
+export function parseEventDef(
+  refined: EventRefined,
+  extra: Dictionary,
+  sourceId: string,
+  allDay: boolean,
+  hasEnd: boolean,
+  context: CalendarContext,
+): EventDef {
   let def: EventDef = {
     title: refined.title || '',
     groupId: refined.groupId || '',
diff --git a/packages/common/src/structs/event-store.ts b/packages/common/src/structs/event-store.ts
index c8e38e2152..24b6999e48 100644
--- a/packages/common/src/structs/event-store.ts
+++ b/packages/common/src/structs/event-store.ts
@@ -86,9 +86,9 @@ export function mergeEventStores(store0: EventStore, store1: EventStore): EventS
 
 export function filterEventStoreDefs(eventStore: EventStore, filterFunc: (eventDef: EventDef) => boolean): EventStore {
   let defs = filterHash(eventStore.defs, filterFunc)
-  let instances = filterHash(eventStore.instances, function(instance: EventInstance) {
-    return defs[instance.defId] // still exists?
-  })
+  let instances = filterHash(eventStore.instances, (instance: EventInstance) => (
+    defs[instance.defId] // still exists?
+  ))
   return { defs, instances }
 }
 
diff --git a/packages/common/src/structs/view-config.tsx b/packages/common/src/structs/view-config.tsx
index 3e3fea0242..5b65840f00 100644
--- a/packages/common/src/structs/view-config.tsx
+++ b/packages/common/src/structs/view-config.tsx
@@ -56,37 +56,34 @@ export interface SpecificViewContentArg extends ViewProps {
 export type SpecificViewMountArg = MountArg<SpecificViewContentArg>
 
 function createViewHookComponent(options: ViewOptions) {
-  return function (viewProps: ViewProps) {
-    return (
-      <ViewContextType.Consumer>
-        {(context: ViewContext) => (
-          <ViewRoot viewSpec={context.viewSpec}>
-            {(rootElRef, viewClassNames) => {
-              let hookProps: SpecificViewContentArg = {
-                ...viewProps,
-                nextDayThreshold: context.options.nextDayThreshold,
-              }
-
-              return (
-                <RenderHook
-                  hookProps={hookProps}
-                  classNames={options.classNames as any}
-                  content={options.content as any}
-                  didMount={options.didMount as any}
-                  willUnmount={options.willUnmount as any}
-                  elRef={rootElRef}
-                >
-                  {(rootElRef, customClassNames, innerElRef, innerContent) => (
-                    <div className={viewClassNames.concat(customClassNames).join(' ')} ref={rootElRef}>
-                      {innerContent}
-                    </div>
-                  )}
-                </RenderHook>
-              )
-            }}
-          </ViewRoot>
-        )}
-      </ViewContextType.Consumer>
-    )
-  }
+  return (viewProps: ViewProps) => (
+    <ViewContextType.Consumer>
+      {(context: ViewContext) => (
+        <ViewRoot viewSpec={context.viewSpec}>
+          {(viewElRef, viewClassNames) => {
+            let hookProps: SpecificViewContentArg = {
+              ...viewProps,
+              nextDayThreshold: context.options.nextDayThreshold,
+            }
+            return (
+              <RenderHook
+                hookProps={hookProps}
+                classNames={options.classNames as any}
+                content={options.content as any}
+                didMount={options.didMount as any}
+                willUnmount={options.willUnmount as any}
+                elRef={viewElRef}
+              >
+                {(rootElRef, customClassNames, innerElRef, innerContent) => (
+                  <div className={viewClassNames.concat(customClassNames).join(' ')} ref={rootElRef}>
+                    {innerContent}
+                  </div>
+                )}
+              </RenderHook>
+            )
+          }}
+        </ViewRoot>
+      )}
+    </ViewContextType.Consumer>
+  )
 }
diff --git a/packages/common/src/structs/view-def.ts b/packages/common/src/structs/view-def.ts
index b790e7c627..0eb4a40be3 100644
--- a/packages/common/src/structs/view-def.ts
+++ b/packages/common/src/structs/view-def.ts
@@ -29,7 +29,12 @@ export function compileViewDefs(defaultConfigs: ViewConfigHash, overrideConfigs:
   return hash
 }
 
-function ensureViewDef(viewType: string, hash: ViewDefHash, defaultConfigs: ViewConfigHash, overrideConfigs: ViewConfigHash): ViewDef | null {
+function ensureViewDef(
+  viewType: string,
+  hash: ViewDefHash,
+  defaultConfigs: ViewConfigHash,
+  overrideConfigs: ViewConfigHash,
+): ViewDef | null {
   if (hash[viewType]) {
     return hash[viewType]
   }
@@ -43,14 +48,19 @@ function ensureViewDef(viewType: string, hash: ViewDefHash, defaultConfigs: View
   return viewDef
 }
 
-function buildViewDef(viewType: string, hash: ViewDefHash, defaultConfigs: ViewConfigHash, overrideConfigs: ViewConfigHash): ViewDef | null {
+function buildViewDef(
+  viewType: string,
+  hash: ViewDefHash,
+  defaultConfigs: ViewConfigHash,
+  overrideConfigs: ViewConfigHash,
+): ViewDef | null {
   let defaultConfig = defaultConfigs[viewType]
   let overrideConfig = overrideConfigs[viewType]
 
-  let queryProp = function (name) {
-    return (defaultConfig && defaultConfig[name] !== null) ? defaultConfig[name] :
+  let queryProp = (name) => (
+    (defaultConfig && defaultConfig[name] !== null) ? defaultConfig[name] :
       ((overrideConfig && overrideConfig[name] !== null) ? overrideConfig[name] : null)
-  }
+  )
 
   let theComponent = queryProp('component') as ViewComponentType
   let superType = queryProp('superType') as string
diff --git a/packages/common/src/structs/view-spec.ts b/packages/common/src/structs/view-spec.ts
index 551d05fee6..fc4e14f0c6 100644
--- a/packages/common/src/structs/view-spec.ts
+++ b/packages/common/src/structs/view-spec.ts
@@ -26,7 +26,12 @@ export interface ViewSpec {
 
 export type ViewSpecHash = { [viewType: string]: ViewSpec }
 
-export function buildViewSpecs(defaultInputs: ViewConfigInputHash, optionOverrides: CalendarOptions, dynamicOptionOverrides: CalendarOptions, localeDefaults): ViewSpecHash {
+export function buildViewSpecs(
+  defaultInputs: ViewConfigInputHash,
+  optionOverrides: CalendarOptions,
+  dynamicOptionOverrides: CalendarOptions,
+  localeDefaults,
+): ViewSpecHash {
   let defaultConfigs = parseViewConfigs(defaultInputs)
   let overrideConfigs = parseViewConfigs(optionOverrides.views)
   let viewDefs = compileViewDefs(defaultConfigs, overrideConfigs)
@@ -34,7 +39,13 @@ export function buildViewSpecs(defaultInputs: ViewConfigInputHash, optionOverrid
   return mapHash(viewDefs, (viewDef) => buildViewSpec(viewDef, overrideConfigs, optionOverrides, dynamicOptionOverrides, localeDefaults))
 }
 
-function buildViewSpec(viewDef: ViewDef, overrideConfigs: ViewConfigHash, optionOverrides: CalendarOptions, dynamicOptionOverrides: CalendarOptions, localeDefaults): ViewSpec {
+function buildViewSpec(
+  viewDef: ViewDef,
+  overrideConfigs: ViewConfigHash,
+  optionOverrides: CalendarOptions,
+  dynamicOptionOverrides: CalendarOptions,
+  localeDefaults,
+): ViewSpec {
   let durationInput =
     viewDef.overrides.duration ||
     viewDef.defaults.duration ||
@@ -60,7 +71,7 @@ function buildViewSpec(viewDef: ViewDef, overrideConfigs: ViewConfigHash, option
     }
   }
 
-  let queryButtonText = function (optionsSubset) {
+  let queryButtonText = (optionsSubset) => {
     let buttonTextMap = optionsSubset.buttonText || {}
     let buttonTextKey = viewDef.defaults.buttonTextKey as string
 
@@ -75,6 +86,8 @@ function buildViewSpec(viewDef: ViewDef, overrideConfigs: ViewConfigHash, option
     if (buttonTextMap[singleUnit] != null) {
       return buttonTextMap[singleUnit]
     }
+
+    return null
   }
 
   return {
diff --git a/packages/common/src/toolbar-parse.ts b/packages/common/src/toolbar-parse.ts
index 5791c8ad0b..dad3565166 100644
--- a/packages/common/src/toolbar-parse.ts
+++ b/packages/common/src/toolbar-parse.ts
@@ -13,8 +13,24 @@ export function parseToolbars(
   calendarApi: CalendarApi,
 ) {
   let viewsWithButtons: string[] = []
-  let headerToolbar = calendarOptions.headerToolbar ? parseToolbar(calendarOptions.headerToolbar, calendarOptions, calendarOptionOverrides, theme, viewSpecs, calendarApi, viewsWithButtons) : null
-  let footerToolbar = calendarOptions.footerToolbar ? parseToolbar(calendarOptions.footerToolbar, calendarOptions, calendarOptionOverrides, theme, viewSpecs, calendarApi, viewsWithButtons) : null
+  let headerToolbar = calendarOptions.headerToolbar ? parseToolbar(
+    calendarOptions.headerToolbar,
+    calendarOptions,
+    calendarOptionOverrides,
+    theme,
+    viewSpecs,
+    calendarApi,
+    viewsWithButtons,
+  ) : null
+  let footerToolbar = calendarOptions.footerToolbar ? parseToolbar(
+    calendarOptions.footerToolbar,
+    calendarOptions,
+    calendarOptionOverrides,
+    theme,
+    viewSpecs,
+    calendarApi,
+    viewsWithButtons,
+  ) : null
 
   return { headerToolbar, footerToolbar, viewsWithButtons }
 }
@@ -66,7 +82,7 @@ function parseSection(
         let buttonText // "
 
         if ((customButtonProps = calendarCustomButtons[buttonName])) {
-          buttonClick = function (ev: UIEvent) {
+          buttonClick = (ev: UIEvent) => {
             if (customButtonProps.click) {
               customButtonProps.click.call(ev.target, ev, ev.target)
             }
@@ -77,14 +93,14 @@ function parseSection(
         } else if ((viewSpec = viewSpecs[buttonName])) {
           viewsWithButtons.push(buttonName)
 
-          buttonClick = function () {
+          buttonClick = () => {
             calendarApi.changeView(buttonName)
           };
           (buttonText = viewSpec.buttonTextOverride) ||
               (buttonIcon = theme.getIconClass(buttonName, isRtl)) ||
               (buttonText = viewSpec.buttonTextDefault)
         } else if (calendarApi[buttonName]) { // a calendarApi method
-          buttonClick = function () {
+          buttonClick = () => {
             calendarApi[buttonName]()
           };
           (buttonText = calendarButtonTextOverrides[buttonName]) ||
diff --git a/packages/common/src/util/runner.ts b/packages/common/src/util/DelayedRunner.ts
similarity index 55%
rename from packages/common/src/util/runner.ts
rename to packages/common/src/util/DelayedRunner.ts
index d6328b4c5f..a12a236ef8 100644
--- a/packages/common/src/util/runner.ts
+++ b/packages/common/src/util/DelayedRunner.ts
@@ -41,7 +41,8 @@ export class DelayedRunner {
       if (force) {
         delete pauseDepths[scope]
       } else {
-        let depth = --pauseDepths[scope]
+        pauseDepths[scope] -= 1
+        let depth = pauseDepths[scope]
 
         if (depth <= 0) {
           delete pauseDepths[scope]
@@ -88,57 +89,3 @@ export class DelayedRunner {
     }
   }
 }
-
-export class TaskRunner<Task> { // this class USES the DelayedRunner
-  private queue: Task[] = []
-
-  private delayedRunner: DelayedRunner // will most likely be used WITHOUT any delay
-
-  constructor(
-    private runTaskOption?: (task: Task) => void,
-    private drainedOption?: (completedTasks: Task[]) => void,
-  ) {
-    this.delayedRunner = new DelayedRunner(this.drain.bind(this))
-  }
-
-  request(task: Task, delay?: number) {
-    this.queue.push(task)
-    this.delayedRunner.request(delay)
-  }
-
-  pause(scope?: string) {
-    this.delayedRunner.pause(scope)
-  }
-
-  resume(scope?: string, force?: boolean) {
-    this.delayedRunner.resume(scope, force)
-  }
-
-  drain() {
-    let { queue } = this
-
-    while (queue.length) {
-      let completedTasks: Task[] = []
-      let task: Task
-
-      while ((task = queue.shift())) {
-        this.runTask(task)
-        completedTasks.push(task)
-      }
-
-      this.drained(completedTasks)
-    } // keep going, in case new tasks were added in the drained handler
-  }
-
-  protected runTask(task: Task) { // subclasses can implement
-    if (this.runTaskOption) {
-      this.runTaskOption(task)
-    }
-  }
-
-  protected drained(completedTasks: Task[]) { // subclasses can implement
-    if (this.drainedOption) {
-      this.drainedOption(completedTasks)
-    }
-  }
-}
diff --git a/packages/common/src/util/RefMap.ts b/packages/common/src/util/RefMap.ts
index 139fd5e9ec..46e4ecc91a 100644
--- a/packages/common/src/util/RefMap.ts
+++ b/packages/common/src/util/RefMap.ts
@@ -30,14 +30,20 @@ export class RefMap<RefType> {
     let added = false
 
     if (val !== null) {
-      removed = (key in currentMap) // for bug... ACTUALLY: can probably do away with this now that callers don't share numeric indices anymore
+      // for bug... ACTUALLY: can probably do away with this now that callers don't share numeric indices anymore
+      removed = (key in currentMap)
+
       currentMap[key] = val
       depths[key] = (depths[key] || 0) + 1
       added = true
-    } else if (--depths[key] === 0) {
-      delete currentMap[key]
-      delete this.callbackMap[key]
-      removed = true
+    } else {
+      depths[key] -= 1
+
+      if (!depths[key]) {
+        delete currentMap[key]
+        delete this.callbackMap[key]
+        removed = true
+      }
     }
 
     if (this.masterCallback) {
diff --git a/packages/common/src/util/TaskRunner.ts b/packages/common/src/util/TaskRunner.ts
new file mode 100644
index 0000000000..007ba1cfc5
--- /dev/null
+++ b/packages/common/src/util/TaskRunner.ts
@@ -0,0 +1,55 @@
+import { DelayedRunner } from './DelayedRunner'
+
+export class TaskRunner<Task> { // this class USES the DelayedRunner
+  private queue: Task[] = []
+
+  private delayedRunner: DelayedRunner // will most likely be used WITHOUT any delay
+
+  constructor(
+    private runTaskOption?: (task: Task) => void,
+    private drainedOption?: (completedTasks: Task[]) => void,
+  ) {
+    this.delayedRunner = new DelayedRunner(this.drain.bind(this))
+  }
+
+  request(task: Task, delay?: number) {
+    this.queue.push(task)
+    this.delayedRunner.request(delay)
+  }
+
+  pause(scope?: string) {
+    this.delayedRunner.pause(scope)
+  }
+
+  resume(scope?: string, force?: boolean) {
+    this.delayedRunner.resume(scope, force)
+  }
+
+  drain() {
+    let { queue } = this
+
+    while (queue.length) {
+      let completedTasks: Task[] = []
+      let task: Task
+
+      while ((task = queue.shift())) {
+        this.runTask(task)
+        completedTasks.push(task)
+      }
+
+      this.drained(completedTasks)
+    } // keep going, in case new tasks were added in the drained handler
+  }
+
+  protected runTask(task: Task) { // subclasses can implement
+    if (this.runTaskOption) {
+      this.runTaskOption(task)
+    }
+  }
+
+  protected drained(completedTasks: Task[]) { // subclasses can implement
+    if (this.drainedOption) {
+      this.drainedOption(completedTasks)
+    }
+  }
+}
diff --git a/packages/common/src/util/dom-event.ts b/packages/common/src/util/dom-event.ts
index 50fdf68775..859439a343 100644
--- a/packages/common/src/util/dom-event.ts
+++ b/packages/common/src/util/dom-event.ts
@@ -13,7 +13,7 @@ export function buildDelegationHandler<EventType extends (Event | VUIEvent)>(
   selector: string,
   handler: (ev: EventType, matchedTarget: HTMLElement) => void,
 ) {
-  return function (ev: EventType) {
+  return (ev: EventType) => {
     let matchedChild = elementClosest(ev.target as HTMLElement, selector)
 
     if (matchedChild) {
@@ -32,7 +32,7 @@ export function listenBySelector(
 
   container.addEventListener(eventType, attachedHandler)
 
-  return function () {
+  return () => {
     container.removeEventListener(eventType, attachedHandler)
   }
 }
@@ -45,14 +45,14 @@ export function listenToHoverBySelector(
 ) {
   let currentMatchedChild
 
-  return listenBySelector(container, 'mouseover', selector, (ev, matchedChild) => {
+  return listenBySelector(container, 'mouseover', selector, (mouseOverEv, matchedChild) => {
     if (matchedChild !== currentMatchedChild) {
       currentMatchedChild = matchedChild
-      onMouseEnter(ev, matchedChild)
+      onMouseEnter(mouseOverEv, matchedChild)
 
-      let realOnMouseLeave = (ev) => {
+      let realOnMouseLeave = (mouseLeaveEv) => {
         currentMatchedChild = null
-        onMouseLeave(ev, matchedChild)
+        onMouseLeave(mouseLeaveEv, matchedChild)
         matchedChild.removeEventListener('mouseleave', realOnMouseLeave)
       }
 
@@ -75,7 +75,7 @@ const transitionEventNames = [
 
 // triggered only when the next single subsequent transition finishes
 export function whenTransitionDone(el: HTMLElement, callback: (ev: Event) => void) {
-  let realCallback = function (ev) {
+  let realCallback = (ev) => {
     callback(ev)
     transitionEventNames.forEach((eventName) => {
       el.removeEventListener(eventName, realCallback)
diff --git a/packages/common/src/util/memoize.ts b/packages/common/src/util/memoize.ts
index 4aacae3dfa..f3c92ff824 100644
--- a/packages/common/src/util/memoize.ts
+++ b/packages/common/src/util/memoize.ts
@@ -10,7 +10,7 @@ export function memoize<Args extends any[], Res>(
   let currentArgs: Args | undefined
   let currentRes: Res | undefined
 
-  return function (...newArgs: Args) {
+  return function (...newArgs: Args) { // eslint-disable-line func-names
     if (!currentArgs) {
       currentRes = workerFunc.apply(this, newArgs)
     } else if (!isArraysEqual(currentArgs, newArgs)) {
@@ -39,7 +39,7 @@ export function memoizeObjArg<Arg extends Dictionary, Res>(
   let currentArg: Arg | undefined
   let currentRes: Res | undefined
 
-  return function (newArg: Arg) {
+  return (newArg: Arg) => {
     if (!currentArg) {
       currentRes = workerFunc.call(this, newArg)
     } else if (!isPropsEqual(currentArg, newArg)) {
@@ -68,7 +68,7 @@ export function memoizeArraylike<Args extends any[], Res>( // used at all?
   let currentArgSets: Args[] = []
   let currentResults: Res[] = []
 
-  return function (newArgSets: Args[]) {
+  return (newArgSets: Args[]) => {
     let currentLen = currentArgSets.length
     let newLen = newArgSets.length
     let i = 0
@@ -110,7 +110,7 @@ export function memoizeHashlike<Args extends any[], Res>( // used?
   let currentArgHash: { [key: string]: Args } = {}
   let currentResHash: { [key: string]: Res } = {}
 
-  return function (newArgHash: { [key: string]: Args }) {
+  return (newArgHash: { [key: string]: Args }) => {
     let newResHash: { [key: string]: Res } = {}
 
     for (let key in newArgHash) {
diff --git a/packages/common/src/util/misc.ts b/packages/common/src/util/misc.ts
index 193c6e7327..b77a160cd5 100644
--- a/packages/common/src/util/misc.ts
+++ b/packages/common/src/util/misc.ts
@@ -5,7 +5,8 @@ export type GenericHash = { [key: string]: any } // already did this somewhere
 let guidNumber = 0
 
 export function guid() {
-  return String(guidNumber += 1)
+  guidNumber += 1
+  return String(guidNumber)
 }
 
 /* FullCalendar-specific DOM Utilities
@@ -155,6 +156,7 @@ export function firstDefined(...args) {
       return args[i]
     }
   }
+  return undefined
 }
 
 /* FC-specific DOM dimension stuff
diff --git a/packages/common/src/util/promise.ts b/packages/common/src/util/promise.ts
index 10c88312b3..c998117718 100644
--- a/packages/common/src/util/promise.ts
+++ b/packages/common/src/util/promise.ts
@@ -6,17 +6,17 @@ export function unpromisify(func, success, failure?) {
   // guard against success/failure callbacks being called more than once
   // and guard against a promise AND callback being used together.
   let isResolved = false
-  let wrappedSuccess = function () {
+  let wrappedSuccess = function () { // eslint-disable-line func-names
     if (!isResolved) {
       isResolved = true
-      success.apply(this, arguments)
+      success.apply(this, arguments) // eslint-disable-line prefer-rest-params
     }
   }
-  let wrappedFailure = function () {
+  let wrappedFailure = function () { // eslint-disable-line func-names
     if (!isResolved) {
       isResolved = true
       if (failure) {
-        failure.apply(this, arguments)
+        failure.apply(this, arguments) // eslint-disable-line prefer-rest-params
       }
     }
   }
diff --git a/packages/common/src/util/requestJson.ts b/packages/common/src/util/requestJson.ts
index d7ad975a15..cecf18ce84 100644
--- a/packages/common/src/util/requestJson.ts
+++ b/packages/common/src/util/requestJson.ts
@@ -18,7 +18,7 @@ export function requestJson(method: string, url: string, params: Dictionary, suc
     xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
   }
 
-  xhr.onload = function () {
+  xhr.onload = () => {
     if (xhr.status >= 200 && xhr.status < 400) {
       let parsed = false
       let res
@@ -40,7 +40,7 @@ export function requestJson(method: string, url: string, params: Dictionary, suc
     }
   }
 
-  xhr.onerror = function () {
+  xhr.onerror = () => {
     failureCallback('Request failed', xhr)
   }
 
diff --git a/packages/common/src/validation.ts b/packages/common/src/validation.ts
index 427944e380..2d1d2c33d5 100644
--- a/packages/common/src/validation.ts
+++ b/packages/common/src/validation.ts
@@ -73,7 +73,9 @@ function isInteractionPropsValid(state: SplittableProps, context: CalendarContex
     subjectConfigs = mapHash(subjectConfigs, filterConfig)
   }
 
-  let otherEventStore = excludeInstances(state.eventStore, interaction.affectedEvents.instances) // exclude the subject events. TODO: exclude defs too?
+  // exclude the subject events. TODO: exclude defs too?
+  let otherEventStore = excludeInstances(state.eventStore, interaction.affectedEvents.instances)
+
   let otherDefs = otherEventStore.defs
   let otherInstances = otherEventStore.instances
   let otherConfigs = compileEventUis(otherDefs, state.eventUiBases)
diff --git a/packages/common/src/vdom-util.tsx b/packages/common/src/vdom-util.tsx
index 508fb674be..f6a2aa714b 100644
--- a/packages/common/src/vdom-util.tsx
+++ b/packages/common/src/vdom-util.tsx
@@ -1,3 +1,5 @@
+/* eslint max-classes-per-file: off */
+
 import { __assign } from 'tslib'
 import { Component, Ref } from './vdom'
 import { ViewContextType, ViewContext } from './ViewContext'
@@ -17,6 +19,7 @@ export abstract class PureComponent<Props=Dictionary, State=Dictionary> extends
 
   shouldComponentUpdate(nextProps: Props, nextState: State) {
     if (this.debug) {
+      // eslint-disable-next-line no-console
       console.log(getUnequalProps(nextProps, this.props), getUnequalProps(nextState, this.state))
     }