为什么 clearInterval 在这段代码中不起作用?

问题描述

有一个使用 setInterval() 设置间隔的函数，但即使在调用 clearInterval() 之后，我也可以在控制台中看到 else 条件仍在运行.如何正确清除该间隔?

There is a function which sets an interval using setInterval(), but even after calling clearInterval(), I can see in the console that the else condition is still running. How can I clear that interval properly?

function increase(old, step, neu) {
    var i = 0;
    var delay2;

    function countUp() {
        if (i < 5) {
            old += step;
            // console.log("increase")
            $("#total-price-value").text(old + " dollors");
            $("#total-price-value").digits();
            i++;
            delay2 = setInterval(countUp, 80);
        } else {
            clearInterval(delay2);
            console.log(delay2);
        }

    }
    countUp();

}​

推荐答案

您似乎对超时和间隔之间的区别有些困惑.超时仅触发一次；间隔多次触发.如果您使用间隔，您可能只想设置一次(您每次都设置它).如果您使用超时，您可能希望每次都设置它(就像您正在做的那样).

It looks like you're a little confused about the difference between timeouts and intervals. Timeouts fire only once; intervals fire many times. If you're using an interval, you probably only want to set it once (you're setting it every time). If you're using a timeout, you probably want to set it every time (like you're doing).

为了解决这个问题，您要么想切换到超时(可能是最简单的；只是搜索/替换)，要么只设置一次间隔.

In order to fix the problem, you'll either want to switch to timeouts (probably the easiest; just a search/replace) or only set the interval once.

例如，以下是如何使用 setTimeout 计数到 5:

For example, here is how one might use setTimeout to count up to five:

var count = 0;
function timeoutFired() {
    count++;
    if(count < 5) {
        setTimeout(timeoutFired, 1000);
    }
}
setTimeout(timeoutFired, 1000);

使用超时，我们不需要清除来阻止它计数；简单地不设置超时将阻止它再次运行.

Using timeouts, we don't need to clear to stop it from counting; simply not setting a timeout will prevent it from running again.

以下是如何使用 setInterval:

var count = 0;
function intervalFired() {
    count++;
    if(count >= 5) {
        clearInterval(interval);
    }
}
var interval = setInterval(intervalFired, 1000);

如果您希望某些使用间隔定期运行的代码停止，您必须调用 clearInterval.请注意，我们只调用 setInterval 一次，而 setTimeout 每次我们不希望它继续.

If you want some code running periodically using intervals to stop, you must call clearInterval. Note that we only call setInterval once, versus setTimeout every time we didn't want it to continue.

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