build: use __DEV__ flag

Author: yyx990803

scripts/config.js

@@ -16,7 +16,7 @@ const banner =
   ' */'
 
 const aliases = require('./alias')
-const resolve = (p) => {
+const resolve = p => {
   const base = p.split('/')[0]
   if (aliases[base]) {
     return path.resolve(aliases[base], p.slice(base.length + 1))
@@ -241,12 +241,13 @@ function genConfig(name) {
     __VERSION__: version
   }
   // feature flags
-  Object.keys(featureFlags).forEach((key) => {
+  Object.keys(featureFlags).forEach(key => {
     vars[`process.env.${key}`] = featureFlags[key]
   })
   // build-specific env
   if (opts.env) {
     vars['process.env.NODE_ENV'] = JSON.stringify(opts.env)
+    vars.__DEV__ = opts.env !== 'production'
   }
 
   vars.preventAssignment = true

src/compiler/codegen/index.ts

@@ -137,7 +137,7 @@ function genOnce(el: ASTElement, state: CodegenState): string {
       parent = parent.parent
     }
     if (!key) {
-      process.env.NODE_ENV !== 'production' &&
+      __DEV__ &&
         state.warn(
           `v-once can only be used inside v-for that is keyed. `,
           el.rawAttrsMap['v-once']
@@ -201,7 +201,7 @@ export function genFor(
   const iterator2 = el.iterator2 ? `,${el.iterator2}` : ''
 
   if (
-    process.env.NODE_ENV !== 'production' &&
+    __DEV__ &&
     state.maybeComponent(el) &&
     el.tag !== 'slot' &&
     el.tag !== 'template' &&
@@ -345,10 +345,7 @@ function genInlineTemplate(
   state: CodegenState
 ): string | undefined {
   const ast = el.children[0]
-  if (
-    process.env.NODE_ENV !== 'production' &&
-    (el.children.length !== 1 || ast.type !== 1)
-  ) {
+  if (__DEV__ && (el.children.length !== 1 || ast.type !== 1)) {
     state.warn(
       'Inline-template components must have exactly one child element.',
       { start: el.start }

src/compiler/create-compiler.ts

@@ -21,10 +21,7 @@ export function createCompilerCreator(baseCompile: Function): Function {
       }
 
       if (options) {
-        if (
-          process.env.NODE_ENV !== 'production' &&
-          options.outputSourceRange
-        ) {
+        if (__DEV__ && options.outputSourceRange) {
           // $flow-disable-line
           const leadingSpaceLength = template.match(/^\s*/)![0].length
 
@@ -69,7 +66,7 @@ export function createCompilerCreator(baseCompile: Function): Function {
       finalOptions.warn = warn
 
       const compiled = baseCompile(template.trim(), finalOptions)
-      if (process.env.NODE_ENV !== 'production') {
+      if (__DEV__) {
         detectErrors(compiled.ast, warn)
       }
       compiled.errors = errors

src/compiler/directives/on.ts

@@ -1,7 +1,7 @@
 import { warn } from 'core/util/index'
 
 export default function on(el: ASTElement, dir: ASTDirective) {
-  if (process.env.NODE_ENV !== 'production' && dir.modifiers) {
+  if (__DEV__ && dir.modifiers) {
     warn(`v-on without argument does not support modifiers.`)
   }
   el.wrapListeners = (code: string) => `_g(${code},${dir.value})`

src/compiler/helpers.ts

@@ -101,12 +101,7 @@ export function addHandler(
   modifiers = modifiers || emptyObject
   // warn prevent and passive modifier
   /* istanbul ignore if */
-  if (
-    process.env.NODE_ENV !== 'production' &&
-    warn &&
-    modifiers.prevent &&
-    modifiers.passive
-  ) {
+  if (__DEV__ && warn && modifiers.prevent && modifiers.passive) {
     warn(
       "passive and prevent can't be used together. " +
         "Passive handler can't prevent default event.",

src/compiler/parser/html-parser.ts

@@ -181,11 +181,7 @@ export function parseHTML(html, options) {
 
     if (html === last) {
       options.chars && options.chars(html)
-      if (
-        process.env.NODE_ENV !== 'production' &&
-        !stack.length &&
-        options.warn
-      ) {
+      if (__DEV__ && !stack.length && options.warn) {
         options.warn(`Mal-formatted tag at end of template: "${html}"`, {
           start: index + html.length
         })
@@ -258,7 +254,7 @@ export function parseHTML(html, options) {
         name: args[1],
         value: decodeAttr(value, shouldDecodeNewlines)
       }
-      if (process.env.NODE_ENV !== 'production' && options.outputSourceRange) {
+      if (__DEV__ && options.outputSourceRange) {
         attrs[i].start = args.start + args[0].match(/^\s*/).length
         attrs[i].end = args.end
       }
@@ -301,11 +297,7 @@ export function parseHTML(html, options) {
     if (pos >= 0) {
       // Close all the open elements, up the stack
       for (let i = stack.length - 1; i >= pos; i--) {
-        if (
-          process.env.NODE_ENV !== 'production' &&
-          (i > pos || !tagName) &&
-          options.warn
-        ) {
+        if (__DEV__ && (i > pos || !tagName) && options.warn) {
           options.warn(`tag <${stack[i].tag}> has no matching end tag.`, {
             start: stack[i].start,
             end: stack[i].end

src/compiler/parser/index.ts

@@ -119,14 +119,14 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
     if (!stack.length && element !== root) {
       // allow root elements with v-if, v-else-if and v-else
       if (root.if && (element.elseif || element.else)) {
-        if (process.env.NODE_ENV !== 'production') {
+        if (__DEV__) {
           checkRootConstraints(element)
         }
         addIfCondition(root, {
           exp: element.elseif,
           block: element
         })
-      } else if (process.env.NODE_ENV !== 'production') {
+      } else if (__DEV__) {
         warnOnce(
           `Component template should contain exactly one root element. ` +
             `If you are using v-if on multiple elements, ` +
@@ -229,7 +229,7 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
         element.ns = ns
       }
 
-      if (process.env.NODE_ENV !== 'production') {
+      if (__DEV__) {
         if (options.outputSourceRange) {
           element.start = start
           element.end = end
@@ -254,7 +254,7 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
 
       if (isForbiddenTag(element) && !isServerRendering()) {
         element.forbidden = true
-        process.env.NODE_ENV !== 'production' &&
+        __DEV__ &&
           warn(
             'Templates should only be responsible for mapping the state to the ' +
               'UI. Avoid placing tags with side-effects in your templates, such as ' +
@@ -289,7 +289,7 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
 
       if (!root) {
         root = element
-        if (process.env.NODE_ENV !== 'production') {
+        if (__DEV__) {
           checkRootConstraints(root)
         }
       }
@@ -307,15 +307,15 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
       // pop stack
       stack.length -= 1
       currentParent = stack[stack.length - 1]
-      if (process.env.NODE_ENV !== 'production' && options.outputSourceRange) {
+      if (__DEV__ && options.outputSourceRange) {
         element.end = end
       }
       closeElement(element)
     },
 
     chars(text: string, start: number, end: number) {
       if (!currentParent) {
-        if (process.env.NODE_ENV !== 'production') {
+        if (__DEV__) {
           if (text === template) {
             warnOnce(
               'Component template requires a root element, rather than just text.',
@@ -382,10 +382,7 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
           }
         }
         if (child) {
-          if (
-            process.env.NODE_ENV !== 'production' &&
-            options.outputSourceRange
-          ) {
+          if (__DEV__ && options.outputSourceRange) {
             child.start = start
             child.end = end
           }
@@ -402,10 +399,7 @@ export function parse(template: string, options: CompilerOptions): ASTElement {
           text,
           isComment: true
         }
-        if (
-          process.env.NODE_ENV !== 'production' &&
-          options.outputSourceRange
-        ) {
+        if (__DEV__ && options.outputSourceRange) {
           child.start = start
           child.end = end
         }
@@ -465,7 +459,7 @@ export function processElement(element: ASTElement, options: CompilerOptions) {
 function processKey(el) {
   const exp = getBindingAttr(el, 'key')
   if (exp) {
-    if (process.env.NODE_ENV !== 'production') {
+    if (__DEV__) {
       if (el.tag === 'template') {
         warn(
           `<template> cannot be keyed. Place the key on real elements instead.`,
@@ -508,7 +502,7 @@ export function processFor(el: ASTElement) {
     const res = parseFor(exp)
     if (res) {
       extend(el, res)
-    } else if (process.env.NODE_ENV !== 'production') {
+    } else if (__DEV__) {
       warn(`Invalid v-for expression: ${exp}`, el.rawAttrsMap['v-for'])
     }
   }
@@ -566,7 +560,7 @@ function processIfConditions(el, parent) {
       exp: el.elseif,
       block: el
     })
-  } else if (process.env.NODE_ENV !== 'production') {
+  } else if (__DEV__) {
     warn(
       `v-${el.elseif ? 'else-if="' + el.elseif + '"' : 'else'} ` +
         `used on element <${el.tag}> without corresponding v-if.`,
@@ -581,7 +575,7 @@ function findPrevElement(children: Array<any>): ASTElement | void {
     if (children[i].type === 1) {
       return children[i]
     } else {
-      if (process.env.NODE_ENV !== 'production' && children[i].text !== ' ') {
+      if (__DEV__ && children[i].text !== ' ') {
         warn(
           `text "${children[i].text.trim()}" between v-if and v-else(-if) ` +
             `will be ignored.`,
@@ -614,7 +608,7 @@ function processSlotContent(el) {
   if (el.tag === 'template') {
     slotScope = getAndRemoveAttr(el, 'scope')
     /* istanbul ignore if */
-    if (process.env.NODE_ENV !== 'production' && slotScope) {
+    if (__DEV__ && slotScope) {
       warn(
         `the "scope" attribute for scoped slots have been deprecated and ` +
           `replaced by "slot-scope" since 2.5. The new "slot-scope" attribute ` +
@@ -627,7 +621,7 @@ function processSlotContent(el) {
     el.slotScope = slotScope || getAndRemoveAttr(el, 'slot-scope')
   } else if ((slotScope = getAndRemoveAttr(el, 'slot-scope'))) {
     /* istanbul ignore if */
-    if (process.env.NODE_ENV !== 'production' && el.attrsMap['v-for']) {
+    if (__DEV__ && el.attrsMap['v-for']) {
       warn(
         `Ambiguous combined usage of slot-scope and v-for on <${el.tag}> ` +
           `(v-for takes higher priority). Use a wrapper <template> for the ` +
@@ -659,7 +653,7 @@ function processSlotContent(el) {
       // v-slot on <template>
       const slotBinding = getAndRemoveAttrByRegex(el, slotRE)
       if (slotBinding) {
-        if (process.env.NODE_ENV !== 'production') {
+        if (__DEV__) {
           if (el.slotTarget || el.slotScope) {
             warn(`Unexpected mixed usage of different slot syntaxes.`, el)
           }
@@ -680,7 +674,7 @@ function processSlotContent(el) {
       // v-slot on component, denotes default slot
       const slotBinding = getAndRemoveAttrByRegex(el, slotRE)
       if (slotBinding) {
-        if (process.env.NODE_ENV !== 'production') {
+        if (__DEV__) {
           if (!maybeComponent(el)) {
             warn(
               `v-slot can only be used on components or <template>.`,
@@ -729,7 +723,7 @@ function getSlotName(binding) {
   if (!name) {
     if (binding.name[0] !== '#') {
       name = 'default'
-    } else if (process.env.NODE_ENV !== 'production') {
+    } else if (__DEV__) {
       warn(`v-slot shorthand syntax requires a slot name.`, binding)
     }
   }
@@ -744,7 +738,7 @@ function getSlotName(binding) {
 function processSlotOutlet(el) {
   if (el.tag === 'slot') {
     el.slotName = getBindingAttr(el, 'name')
-    if (process.env.NODE_ENV !== 'production' && el.key) {
+    if (__DEV__ && el.key) {
       warn(
         `\`key\` does not work on <slot> because slots are abstract outlets ` +
           `and can possibly expand into multiple elements. ` +
@@ -791,10 +785,7 @@ function processAttrs(el) {
         if (isDynamic) {
           name = name.slice(1, -1)
         }
-        if (
-          process.env.NODE_ENV !== 'production' &&
-          value.trim().length === 0
-        ) {
+        if (__DEV__ && value.trim().length === 0) {
           warn(
             `The value for a v-bind expression cannot be empty. Found in "v-bind:${name}"`
           )
@@ -885,13 +876,13 @@ function processAttrs(el) {
           modifiers,
           list[i]
         )
-        if (process.env.NODE_ENV !== 'production' && name === 'model') {
+        if (__DEV__ && name === 'model') {
           checkForAliasModel(el, value)
         }
       }
     } else {
       // literal attribute
-      if (process.env.NODE_ENV !== 'production') {
+      if (__DEV__) {
         const res = parseText(value, delimiters)
         if (res) {
           warn(
@@ -942,12 +933,7 @@ function parseModifiers(name: string): Object | void {
 function makeAttrsMap(attrs: Array<Record<string, any>>): Record<string, any> {
   const map = {}
   for (let i = 0, l = attrs.length; i < l; i++) {
-    if (
-      process.env.NODE_ENV !== 'production' &&
-      map[attrs[i].name] &&
-      !isIE &&
-      !isEdge
-    ) {
+    if (__DEV__ && map[attrs[i].name] && !isIE && !isEdge) {
       warn('duplicate attribute: ' + attrs[i].name, attrs[i])
     }
     map[attrs[i].name] = attrs[i].value

src/compiler/to-function.ts

@@ -30,7 +30,7 @@ export function createCompileToFunctionFn(compile: Function): Function {
     delete options.warn
 
     /* istanbul ignore if */
-    if (process.env.NODE_ENV !== 'production') {
+    if (__DEV__) {
       // detect possible CSP restriction
       try {
         new Function('return 1')
@@ -59,7 +59,7 @@ export function createCompileToFunctionFn(compile: Function): Function {
     const compiled = compile(template, options)
 
     // check compilation errors/tips
-    if (process.env.NODE_ENV !== 'production') {
+    if (__DEV__) {
       if (compiled.errors && compiled.errors.length) {
         if (options.outputSourceRange) {
           compiled.errors.forEach(e => {
@@ -99,7 +99,7 @@ export function createCompileToFunctionFn(compile: Function): Function {
     // this should only happen if there is a bug in the compiler itself.
     // mostly for codegen development use
     /* istanbul ignore if */
-    if (process.env.NODE_ENV !== 'production') {
+    if (__DEV__) {
       if ((!compiled.errors || !compiled.errors.length) && fnGenErrors.length) {
         warn(
           `Failed to generate render function:\n\n` +

src/core/config.ts

@@ -45,12 +45,12 @@ export default {
   /**
    * Show production mode tip message on boot?
    */
-  productionTip: process.env.NODE_ENV !== 'production',
+  productionTip: __DEV__,
 
   /**
    * Whether to enable devtools
    */
-  devtools: process.env.NODE_ENV !== 'production',
+  devtools: __DEV__,
 
   /**
    * Whether to record perf