fix(b-table): minor code optimizations to filter debouncing (#4167)

src/components/table/helpers/mixin-filtering.js

@@ -96,21 +96,18 @@ export default {
       // We need a deep watcher in case the user passes
       // an object when using `filter-function`
       deep: true,
-      handler(newFilter, oldFilter) {
+      handler(newCriteria, oldCriteria) {
         const timeout = this.computedFilterDebounce
-        if (this.$_filterTimer) {
-          clearTimeout(this.$_filterTimer)
-          this.$_filterTimer = null
-        }
-        if (timeout) {
+        clearTimeout(this.$_filterTimer)
+        this.$_filterTimer = null
+        if (timeout && timeout > 0) {
           // If we have a debounce time, delay the update of `localFilter`
           this.$_filterTimer = setTimeout(() => {
-            this.$_filterTimer = null
-            this.localFilter = this.filterSanitize(this.filter)
+            this.localFilter = this.filterSanitize(newCriteria)
           }, timeout)
         } else {
           // Otherwise, immediately update `localFilter` with `newFilter` value
-          this.localFilter = this.filterSanitize(newFilter)
+          this.localFilter = this.filterSanitize(newCriteria)
         }
       }
     },
@@ -154,12 +151,9 @@ export default {
       this.isFiltered = Boolean(this.localFilter)
     })
   },
-  beforeDestroy() {
-    /* istanbul ignore next */
-    if (this.$_filterTimer) {
-      clearTimeout(this.$_filterTimer)
-      this.$_filterTimer = null
-    }
+  beforeDestroy() /* istanbul ignore next */ {
+    clearTimeout(this.$_filterTimer)
+    this.$_filterTimer = null
   },
   methods: {
     filterSanitize(criteria) {

src/components/table/table-filtering.spec.js

@@ -238,6 +238,7 @@ describe('table > filtering', () => {
 
   it('filter debouncing works', async () => {
     jest.useFakeTimers()
+    let lastFilterTimer = null
     const wrapper = mount(BTable, {
       propsData: {
         fields: testFields,
@@ -254,6 +255,7 @@ describe('table > filtering', () => {
     expect(wrapper.emitted('input').length).toBe(1)
     expect(wrapper.emitted('input')[0][0]).toEqual(testItems)
     expect(wrapper.vm.$_filterTimer).toBe(null)
+    lastFilterTimer = wrapper.vm.$_filterTimer
 
     // Set filter to a single character
     wrapper.setProps({
@@ -262,6 +264,9 @@ describe('table > filtering', () => {
     await waitNT(wrapper.vm)
     expect(wrapper.emitted('input').length).toBe(1)
     expect(wrapper.vm.$_filterTimer).not.toBe(null)
+    expect(wrapper.vm.$_filterTimer).not.toEqual(lastFilterTimer)
+    lastFilterTimer = wrapper.vm.$_filterTimer
+    expect(wrapper.vm.localFilter).not.toEqual('1')
 
     // Change filter
     wrapper.setProps({
@@ -270,12 +275,17 @@ describe('table > filtering', () => {
     await waitNT(wrapper.vm)
     expect(wrapper.emitted('input').length).toBe(1)
     expect(wrapper.vm.$_filterTimer).not.toBe(null)
+    expect(wrapper.vm.$_filterTimer).not.toEqual(lastFilterTimer)
+    lastFilterTimer = wrapper.vm.$_filterTimer
+    expect(wrapper.vm.localFilter).not.toEqual('z')
 
     jest.runTimersToTime(101)
     await waitNT(wrapper.vm)
     expect(wrapper.emitted('input').length).toBe(2)
     expect(wrapper.emitted('input')[1][0]).toEqual([testItems[2]])
-    expect(wrapper.vm.$_filterTimer).toBe(null)
+    expect(wrapper.vm.$_filterTimer).toEqual(lastFilterTimer)
+    lastFilterTimer = wrapper.vm.$_filterTimer
+    expect(wrapper.vm.localFilter).toEqual('z')
 
     // Change filter
     wrapper.setProps({
@@ -284,6 +294,10 @@ describe('table > filtering', () => {
     await waitNT(wrapper.vm)
     expect(wrapper.vm.$_filterTimer).not.toBe(null)
     expect(wrapper.emitted('input').length).toBe(2)
+    expect(wrapper.vm.$_filterTimer).not.toEqual(lastFilterTimer)
+    lastFilterTimer = wrapper.vm.$_filterTimer
+    expect(wrapper.vm.localFilter).not.toEqual('1')
+    expect(wrapper.vm.localFilter).toEqual('z')
 
     // Change filter-debounce to no debouncing
     wrapper.setProps({
@@ -295,6 +309,7 @@ describe('table > filtering', () => {
     // Should immediately filter the items
     expect(wrapper.emitted('input').length).toBe(3)
     expect(wrapper.emitted('input')[2][0]).toEqual([testItems[1]])
+    expect(wrapper.vm.localFilter).toEqual('1')
 
     wrapper.destroy()
   })