setTimeout能否返回0作为id？ [英] Can setTimeout ever return 0 as the id?

问题描述

我正在写一张支票，看看超时是否有效。我想这样做：

I am writing a check to see if a timeout is active. I was thinking of doing this:

var a = setTimeout(fn, 10);
// ... Other code ... where clearTimeout(a) can be called and set to null
if (a != null)
{
   // do soemthing
}

我想知道a是否有可能是0。那个案子我会用 a！== null

I was wondering if it would ever be possible that a will be 0. In that case I would use a !== null

推荐答案

首先： 0与null不同，（0 == null）在每种情况下都为false';

First: 0 isn't the same as null, (0 == null) would be false in every case';

如果你想对某些东西测试'a'：define首先'a'然后将settimeout分配给'a'。然后检查'a'的类型。如果它'未定义'，则计时器尚未触发

if you want to test 'a' against something: define 'a' first and later assign the settimeout to 'a'. then check against the type of 'a'. If its 'undefined', the timer hasn't triggered yet

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