Javascript 检查超时是否已清除？
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原文地址: http://stackoverflow.com/questions/5226578/
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Check if a timeout has been cleared?
提问by chobo2
I am wondering is there a way to tell if a timeout is still set
我想知道有没有办法判断超时是否仍然设置
var t=setTimeout("alertMsg()",3000);
I thought t would be like undefined when you clear it. But it seems to have some id that does not get cleared.
当你清除它时，我认为 t 会像 undefined 。但它似乎有一些没有被清除的 id。
回答by Reid
Not directly, but you can create a wrapper object to give that functionality. A rough implementation is like so:
不是直接的，但您可以创建一个包装对象来提供该功能。粗略的实现是这样的：
function Timeout(fn, interval) {
var id = setTimeout(fn, interval);
this.cleared = false;
this.clear = function () {
this.cleared = true;
clearTimeout(id);
};
}
Then you can do something like:
然后你可以做这样的事情：
var t = new Timeout(function () {
alert('this is a test');
}, 5000);
console.log(t.cleared); // false
t.clear();
console.log(t.cleared); // true
回答by jordancpaul
First of all, I am giving credit to Reid for portions of this answer, however I felt that I should add some suggestions. With my slight additions to Reid's code, this will:
首先，我将这个答案的一部分归功于里德，但我觉得我应该添加一些建议。我对 Reid 的代码稍加添加，这将：
- auto-clear when the timeout naturally expires
- optionally set the scope of the timeout function (rather than just executing in global scope).
- optionally pass arguments array to the timeout function
- 超时自然到期时自动清除
- 可选地设置超时函数的范围（而不仅仅是在全局范围内执行）。
- 可选地将参数数组传递给超时函数
here it is:
这里是：
function Timeout(fn, interval, scope, args) {
scope = scope || window;
var self = this;
var wrap = function(){
self.clear();
fn.apply(scope, args || arguments);
}
this.id = setTimeout(wrap, interval);
}
Timeout.prototype.id = null
Timeout.prototype.cleared = false;
Timeout.prototype.clear = function () {
clearTimeout(this.id);
this.cleared = true;
this.id = null;
};
[begin comment-free plug]Oh, and I am using the prototype model of adding methods to classes, but only because I prefer it, not because I feel it is more correct [end comment-free plug]
[开始免评论插件]哦，我用的是给类添加方法的原型模型，只是因为我喜欢它，而不是因为我觉得它更正确 [结束免评论插件]
回答by Gavin
Just set tto 0(or t in your case) in your timeout function:
只需在超时函数中设置t为0（或在您的情况下为 t）：
timeoutID = 0;
If you use clearTimeoutit sets the timeout id to 0, so checking for timeoutID === 0will check if it's either been been cleared or completed.
如果您使用clearTimeout它，则将超时 ID 设置为 0，因此检查timeoutID === 0将检查它是否已被清除或已完成。
回答by user113716
No. In order to know, you'll need to null the tvariable after you call clearTimeout. Otherwise there's really no indicator.
不。为了知道，您需要t在调用clearTimeout. 否则真的没有指标。
And FYI, it's better to pass a direct reference to the function instead of a string that will be eval'd.
仅供参考，最好传递对函数的直接引用，而不是将被评估的字符串。
var t=setTimeout(alertMsg,3000);
回答by Jesper Wilfing
Like some users suggests in comments, whenever the timeout is either triggered (after the set time has passed) or cleared with clearTimeout, set it manually to falseor preferably null. Then you can perform a simple if-check to see if it is active. Also remember to initialize it as false/nullif needed.
就像一些用户在评论中建议的那样，无论何时触发超时（在设置的时间过后）或使用 清除clearTimeout，手动将其设置为false或最好设置为null。然后您可以执行一个简单的 if 检查以查看它是否处于活动状态。还记得将它初始化为false/null如果需要。
Created a small test page for this: https://codepen.io/TheJesper/pen/rJzava
为此创建了一个小测试页面：https: //codepen.io/TheJesper/pen/rJzava
回答by Oleg
There is another way to check a presence of the timeout. Value which holds a timeout has for default a number value which is increasing with time. So we can do next in "if" construction:
还有另一种方法可以检查超时是否存在。默认情况下，持有超时的值具有随时间增加的数字值。所以我们可以在“if”构造中做下一步：
if (someBooleanValue && !parseInt(@changeToCriteriaTimeout) > 0){
//Do something
}
