setTimeout如何防止潜在的stackoverflow [英] how does setTimeout prevent potential stackoverflow

问题描述

一个例子：

var list = readHugeList();

var nextListItem = function() {
    var item = list.pop();

    if (item) {
        setTimeout( nextListItem, 0);
        // ^^^^^^^^ this line
    }
};

如何使用setTimeout来防止潜在的堆栈溢出？我理解事件队列的概念以及堆栈，但我很难连接两者。

How does use of setTimeout prevent potential stackoverflow here? I understand concept of event queue as well as stack, but I'm having difficulty connecting the two.

推荐答案

设置超时不会导致堆栈溢出，因为它是异步的。它只会将回调放到事件队列中而不会阻止执行。


在第一种情况下：

setTimeout只是将回调放入事件队列，而父函数在没有占用堆栈的情况下退出。

即使超时是0毫秒，它也会在下一个事件循环中调用，因此不会阻止执行中的代码

setTimeout just puts the callback to event queue and the parent function exits after without busying the stack.
Even though the timeout is 0 ms, it will be called in the next event loop, thus not blocking the code in execution

var nextListItem = function() {
    var item = list.pop();

    if (item) {
         setTimeout( nextListItem, 0);
    }
};

在第二种情况下：


Parent调用子函数将新条目放入堆栈，即使父项未从堆栈中清除。

最终更多的递归调用会使堆栈失效。

In the second case:

Parent call the child function putting new entry into stack, even though the parents is not cleared from the stack.
Eventually more recursive calls would blow the stack.

var nextListItem = function() {
        var item = list.pop();

        if (item) {        
           nextListItem();
        }
    };

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