jQuery的.delay方法如何在引擎盖下工作？ [英] How does jQuery's .delay method work under-the-hood?

问题描述

我刚看到这个并认为它很酷。

I just saw this and think it's cool.

console.log("Starting...");
$("#my_element")
  .fadeIn()
  .delay(3000)
  .fadeOut();
console.log("Finishing...");

.delay方法如何在引擎盖下工作？我的意思是，它是如何弄清楚如何等待3秒而不是中断主控制流程？

How does the .delay method work under-the-hood? I mean, how does it figure out how to wait 3 seconds but not interrupt the main control flow?

推荐答案

jQuery有内部queue对象，这只是一个数组：

jQuery has an internal "queue" object, that is just an array:

[ nextAction,
  action,
  action,
  lastAction ]

当你使用延迟时，它推动：

function delay( ms ){
   setTimeout( dequeue, ms )
}

这意味着一旦达到延迟，就会超时，然后触发下一个动作。然而，立即发生的操作，如 .css ，请执行：

Meaning that once it gets to the delay, there's a timeout and then the next action is fired. Actions that happen immediately, like .css, however, do:

function css(){
    // do stuff
    dequeue();
}

没有延迟。

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