fix: check enterToClass/leaveToClass existence before adding it (#5912)

jkzing · yyx990803 · commit 34d8c796ac6a · 2017-06-30T14:57:16.000+08:00
related: #5800
diff --git a/src/platforms/web/runtime/transition-util.js b/src/platforms/web/runtime/transition-util.js
@@ -69,8 +69,11 @@ export function nextFrame (fn: Function) {
 }
 
 export function addTransitionClass (el: any, cls: string) {
-  (el._transitionClasses || (el._transitionClasses = [])).push(cls)
-  addClass(el, cls)
+  const transitionClasses = el._transitionClasses || (el._transitionClasses = [])
+  if (transitionClasses.indexOf(cls) < 0) {
+    transitionClasses.push(cls)
+    addClass(el, cls)
+  }
 }
 
 export function removeTransitionClass (el: any, cls: string) {

Original file line number	Diff line number	Diff line change
`@@ -69,8 +69,11 @@ export function nextFrame (fn: Function) {`
`69`	`69`	`}`
`70`	`70`
`71`	`71`	`export function addTransitionClass (el: any, cls: string) {`
`72`		`- (el._transitionClasses \|\| (el._transitionClasses = [])).push(cls)`
`73`		`- addClass(el, cls)`
	`72`	`+ const transitionClasses = el._transitionClasses \|\| (el._transitionClasses = [])`
	`73`	`+ if (transitionClasses.indexOf(cls) < 0) {`
	`74`	`+ transitionClasses.push(cls)`
	`75`	`+ addClass(el, cls)`
	`76`	`+ }`
`74`	`77`	`}`
`75`	`78`
`76`	`79`	`export function removeTransitionClass (el: any, cls: string) {`