eval 和 setTimeout 循环

发布于 2024-11-25 14:05:28 字数 494 浏览 0 评论 0原文

我将代码行保存在数组中，并尝试使用 setTimeout() 逐个单元地运行它们。

这可以很好地执行代码：

for (i=0; i<restorePoints.length; i++){
    eval(restorePoints[i]);
}

但我希望每次迭代之间有一个短暂的延迟：我想使用 setTimeout() 而不是 eval()。由于某种原因，这些都不起作用：

for (i=0; i<restorePoints.length; i++){
    setTimeout(restorePoints[i],1000);
}

或者

for (i=0; i<restorePoints.length; i++){
    setTimeout(eval(restorePoints[i]),1000);
}

我该怎么做？谢谢

原文

I'm holding code lines in an array, and trying to run them cell by cell with setTimeout().

This executes the code well:

for (i=0; i<restorePoints.length; i++){
    eval(restorePoints[i]);
}

but I want to have a short delay between every iteration: i want to use setTimeout() instead of eval(). for some reason none of those work:

for (i=0; i<restorePoints.length; i++){
    setTimeout(restorePoints[i],1000);
}

for (i=0; i<restorePoints.length; i++){
    setTimeout(eval(restorePoints[i]),1000);
}

how do I do it?
thanks

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黯淡〆 2024-12-02 14:05:28

循环很快。它将连续创建所有超时，因此所有超时将同时触发。您可以使时间取决于循环变量，即增加每次迭代的时间，或者，我会做的，仅使用一次超时和递归调用：

(function() {
    var data = restorePoints;
    var run = function(i) {
        setTimeout(function() {
            var entry = data[i];
            if(entry) {
                eval(entry);
                run(i+1);
            }
        }, 1000);
    };
    run(0);
}());

请注意， eval(string) 和 eval(string) 之间存在差异和 setTimeout(string, ...) 除了延迟之外：

eval 将在当前范围内评估参数，而 setTimeout （和setInterval) 将在全局范围内对其进行评估。

这可能与您相关。

The loop is fast. It will create all timeouts in a row, so all timeouts will fire at the same time. You can either make the time depended on the loop variable, i.e. increasing the time in every iteration, or, what I would do, use only one timeout and a recursive call:

(function() {
    var data = restorePoints;
    var run = function(i) {
        setTimeout(function() {
            var entry = data[i];
            if(entry) {
                eval(entry);
                run(i+1);
            }
        }, 1000);
    };
    run(0);
}());

Note that there is a difference between eval(string) and setTimeout(string, ...) apart from the delay:

eval will evaluate the parameter in the current scope while setTimeout (and setInterval) will evaluate it in the global scope.

This might be relevant to you.

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臻嫒无言 2024-12-02 14:05:28

如果您打算采用其中任何一种方式，则需要将函数调用包装在匿名函数中：

for (i=0; i<restorePoints.length; i++){
    setTimeout(function(){eval(restorePoints[i]}),1000);
}

否则，您不会将 eval 设置为在超时时触发，而是设置执行的结果setTimeout 所针对的对象是 Javascript 代码（无论在本例中是什么）。

If you're going to do it either of those ways, you'll need to wrap the function call in an anonymous function:

for (i=0; i<restorePoints.length; i++){
    setTimeout(function(){eval(restorePoints[i]}),1000);
}

Otherwise you're not setting the eval to fire in a timeout, you're setting the result of the executing Javascript code (whatever that might be in this case) to be the thing setTimeout is opperating against.

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