prioritize the MutationObserver (microtask) approach

勾股 · 勾股 · commit 38accc1755df · 2016-01-21T20:52:32.000+08:00
diff --git a/src/util/env.js b/src/util/env.js
@@ -72,9 +72,7 @@ export const nextTick = (function () {
   }
 
   /* istanbul ignore if */
-  if (typeof setImmediate === 'function') {
-    timerFunc = setImmediate
-  } else if (typeof MutationObserver !== 'undefined') {
+  if (typeof MutationObserver !== 'undefined') {
     var counter = 1
     var observer = new MutationObserver(nextTickHandler)
     var textNode = document.createTextNode(counter)
@@ -85,6 +83,8 @@ export const nextTick = (function () {
       counter = (counter + 1) % 2
       textNode.data = counter
     }
+  } else if (typeof setImmediate === 'function') {
+    timerFunc = setImmediate
   } else {
     timerFunc = setTimeout
   }

Original file line number	Diff line number	Diff line change
`@@ -72,9 +72,7 @@ export const nextTick = (function () {`
`72`	`72`	`}`
`73`	`73`
`74`	`74`	`/* istanbul ignore if */`
`75`		`- if (typeof setImmediate === 'function') {`
`76`		`- timerFunc = setImmediate`
`77`		`- } else if (typeof MutationObserver !== 'undefined') {`
	`75`	`+ if (typeof MutationObserver !== 'undefined') {`
`78`	`76`	`var counter = 1`
`79`	`77`	`var observer = new MutationObserver(nextTickHandler)`
`80`	`78`	`var textNode = document.createTextNode(counter)`
`@@ -85,6 +83,8 @@ export const nextTick = (function () {`
`85`	`83`	`counter = (counter + 1) % 2`
`86`	`84`	`textNode.data = counter`
`87`	`85`	`}`
	`86`	`+ } else if (typeof setImmediate === 'function') {`
	`87`	`+ timerFunc = setImmediate`
`88`	`88`	`} else {`
`89`	`89`	`timerFunc = setTimeout`
`90`	`90`	`}`