scope中的两个异步方法.doc

scope中的两个异步方法 Angular中digest循环的主干是对于watchers的若干次遍历，直到整个scope中的数据”稳定”下来，这部分实现在这篇文章中已经进行了详尽的介绍。相关的一些细节优化也在这篇文章中进行了分析。 除了主干的内容，digest循环的内容其实还包括几个比较有趣的部分，比如这一节我们即将分析的$evalAsync以及$applyAsync，下面我们就来通过相关源代码来分析一下： $digest: function() { var watch, value, last, fn, get, watchers, length, dirty, ttl = TTL, next, current, target = this, watchLog = [], logIdx, logMsg, asyncTask; beginPhase($digest); // Check for changes to browser url that happened in sync before the call to $digest $browser.$$checkUrlChange(); if (this === $rootScope applyAsyncId !== null) { // If this is the root scope, and $applyAsync has scheduled a deferred $apply(), then // cancel the scheduled $apply and flush the queue of expressions to be evaluated. $browser.defer.cancel(applyAsyncId); flushApplyAsync(); } lastDirtyWatch = null; do { // while dirty loop dirty = false; current = target; while (asyncQueue.length) { try { asyncTask = asyncQueue.shift(); asyncTask.scope.$eval(asyncTask.expression, asyncTask.locals); } catch (e) { $exceptionHandler(e); } lastDirtyWatch = null; } traverseScopesLoop: do { // traverse the scopes loop if ((watchers = current.$$watchers)) { // process our watches length = watchers.length; while (length--) { try { watch = watchers[length]; // Most common watches are on primitives, in which case we can short // circuit it with === operator, only when === fails do we use .equals if (watch) { get = watch.get; if ((value = get(current)) !== (last = watch.last) !(watch.eq ? equals(value, last) : (typeof value === number typeof last === number isNaN(value) isNaN(last)))) { dirty = true; lastDirtyWatch = watch;