fix .once with other modifiers that prevent execution of a handler (fix

#4846)

src/compiler/codegen/events.js

@@ -19,11 +19,14 @@ const keyCodes: { [key: string]: number | Array<number> } = {
 const modifierCode: { [key: string]: string } = {
   stop: '$event.stopPropagation();',
   prevent: '$event.preventDefault();',
-  self: 'if($event.target !== $event.currentTarget)return;',
-  ctrl: 'if(!$event.ctrlKey)return;',
-  shift: 'if(!$event.shiftKey)return;',
-  alt: 'if(!$event.altKey)return;',
-  meta: 'if(!$event.metaKey)return;'
+  // #4868: modifiers that prevent the execution of the listener
+  // need to explicitly return null so that we can determine whether to remove
+  // the listener for .once
+  self: 'if($event.target !== $event.currentTarget)return null;',
+  ctrl: 'if(!$event.ctrlKey)return null;',
+  shift: 'if(!$event.shiftKey)return null;',
+  alt: 'if(!$event.altKey)return null;',
+  meta: 'if(!$event.metaKey)return null;'
 }
 
 export function genHandlers (events: ASTElementHandlers, native?: boolean): string {
@@ -62,12 +65,12 @@ function genHandler (
     const handlerCode = simplePathRE.test(handler.value)
       ? handler.value + '($event)'
       : handler.value
-    return 'function($event){' + code + handlerCode + '}'
+    return `function($event){${code}${handlerCode}}`
   }
 }
 
 function genKeyFilter (keys: Array<string>): string {
-  return `if(${keys.map(genFilterCode).join('&&')})return;`
+  return `if(${keys.map(genFilterCode).join('&&')})return null;`
 }
 
 function genFilterCode (key: string): string {

src/core/vdom/helpers/update-listeners.js

@@ -32,7 +32,8 @@ function createEventHandle (fn: Function | Array<Function>): {
           fn[i].apply(null, arguments)
         }
       } else {
-        fn.apply(null, arguments)
+        // return handler return value for single handlers
+        return fn.apply(null, arguments)
       }
     }
   }

src/platforms/web/runtime/modules/events.js

@@ -14,10 +14,12 @@ function add (
     const oldHandler = handler
     const _target = target // save current target element in closure
     handler = function (ev) {
-      remove(event, handler, capture, _target)
-      arguments.length === 1
+      const res = arguments.length === 1
         ? oldHandler(ev)
         : oldHandler.apply(null, arguments)
+      if (res !== null) {
+        remove(event, handler, capture, _target)
+      }
     }
   }
   target.addEventListener(event, handler, capture)

test/unit/features/directives/on.spec.js

@@ -173,6 +173,21 @@ describe('Directive v-on', () => {
     expect(callOrder.toString()).toBe('1,2,2')
   })
 
+  // #4846
+  it('should support once and other modifiers', () => {
+    vm = new Vue({
+      el,
+      template: `<div @click.once.self="foo"><span/></div>`,
+      methods: { foo: spy }
+    })
+    triggerEvent(vm.$el.firstChild, 'click')
+    expect(spy).not.toHaveBeenCalled()
+    triggerEvent(vm.$el, 'click')
+    expect(spy).toHaveBeenCalled()
+    triggerEvent(vm.$el, 'click')
+    expect(spy.calls.count()).toBe(1)
+  })
+
   it('should support keyCode', () => {
     vm = new Vue({
       el,

test/unit/modules/compiler/codegen.spec.js

@@ -229,27 +229,27 @@ describe('codegen', () => {
   it('generate events with keycode', () => {
     assertCodegen(
       '<input @input.enter="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(_k($event.keyCode,"enter",13))return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(_k($event.keyCode,"enter",13))return null;onInput($event)}}})}`
     )
     // multiple keycodes (delete)
     assertCodegen(
       '<input @input.delete="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(_k($event.keyCode,"delete",[8,46]))return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(_k($event.keyCode,"delete",[8,46]))return null;onInput($event)}}})}`
     )
     // multiple keycodes (chained)
     assertCodegen(
       '<input @keydown.enter.delete="onInput">',
-      `with(this){return _c('input',{on:{"keydown":function($event){if(_k($event.keyCode,"enter",13)&&_k($event.keyCode,"delete",[8,46]))return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"keydown":function($event){if(_k($event.keyCode,"enter",13)&&_k($event.keyCode,"delete",[8,46]))return null;onInput($event)}}})}`
     )
     // number keycode
     assertCodegen(
       '<input @input.13="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if($event.keyCode!==13)return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if($event.keyCode!==13)return null;onInput($event)}}})}`
     )
     // custom keycode
     assertCodegen(
       '<input @input.custom="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(_k($event.keyCode,"custom"))return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(_k($event.keyCode,"custom"))return null;onInput($event)}}})}`
     )
   })
 
@@ -264,33 +264,33 @@ describe('codegen', () => {
     )
     assertCodegen(
       '<input @input.self="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if($event.target !== $event.currentTarget)return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if($event.target !== $event.currentTarget)return null;onInput($event)}}})}`
     )
   })
 
   it('generate events with mouse event modifiers', () => {
     assertCodegen(
       '<input @click.ctrl="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.shift="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.shiftKey)return;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.shiftKey)return null;onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.alt="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.altKey)return;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.altKey)return null;onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.meta="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.metaKey)return;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.metaKey)return null;onClick($event)}}})}`
     )
   })
 
   it('generate events with multiple modifers', () => {
     assertCodegen(
       '<input @input.stop.prevent.self="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){$event.stopPropagation();$event.preventDefault();if($event.target !== $event.currentTarget)return;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){$event.stopPropagation();$event.preventDefault();if($event.target !== $event.currentTarget)return null;onInput($event)}}})}`
     )
   })