Javascript 引擎的單線程特性使得在處理一個較大的循環遍歷時會長時間獨占線程，導致其它事件（例如用戶操作）無法及時響應，嚴重時造成卡頓甚至是假死現象。為解決上述問題，一種可行機制是將大的循環拆分成若干小的循環片段分片執行，使得Javascript 引擎有時機在各段之間插入執行其它事情，從而有效改善性能體驗
Ansync.js
複製代碼代碼如下:
function Ansync (totalCount, segmentCount, workCallback, returnCallback)
{
var num_of_item_for_each_segment = segmentCount;
var num_of_segment = Math.ceil(totalCount / num_of_item_for_each_segment);
var count_of_segment = 0;
var timer;
var start, end;
this.process = function(scope, timeout)
{
if (scope != undefined)
{
workCallback = workCallback.bind(scope);
returnCallback = returnCallback ? returnCallback.bind(scope) : undefined;
}
if (count_of_segment == num_of_segment)
{
clearTimeout(timer);
if (returnCallback != undefined)
returnCallback();
}
else
{
start = count_of_segment * num_of_item_for_each_segment;
end = Math.min(totalCount, (count_of_segment + 1) * num_of_item_for_each_segment);
if (num_of_segment == 1)//needn't create timer
{
workCallback(start, end);
count_of_segment = 1;
this.process();
}
else
{
timer = setTimeout(function ansyncTimeout(){
if (workCallback(start, end)) //finish process if function returns true
{
count_of_segment = num_of_segment;
}
else
{
count_of_segment++;
}
this.scope.process();
}.bind({scope: this}),timeout == undefined ? Ansync.TimeOut : timeout);
}
}
}
}
Ansync.TimeOut = 5;
方法很簡單，但是很實用，有相同項目需求的小伙伴參考下吧