自调用函数内的递归函数上的 setTimeout()

发布于 2024-12-26 05:06:03 字数 450 浏览 2 评论 0原文

我想将我的代码作为自调用匿名函数分发，正如我看到的许多人所做的那样。另外，在我的代码中，我必须监视另一个库的加载，这样我就可以在它可用时使用它。

(function(window, document, undefined) {
  staffHappens();
  var initMyLib = function() {
    if (typeof(myLib) == 'undefined') {
      setTimeout("initMyLib()", 50);
    } else {
      useMyLib();
    }
  }
  moreStaffHappens();
  initMyLib(); //-> initMyLib is undefined
})(this, document);

怎么会出现这个错误呢？ initMyLib 应该在封闭（自调用）函数的范围内吗？

原文

I want to distribute my code as a self-envoking anonymous functions, as I see many do. Also, within my code I have to monitor for another lib loading, so I can use it when it's available.

(function(window, document, undefined) {
  staffHappens();
  var initMyLib = function() {
    if (typeof(myLib) == 'undefined') {
      setTimeout("initMyLib()", 50);
    } else {
      useMyLib();
    }
  }
  moreStaffHappens();
  initMyLib(); //-> initMyLib is undefined
})(this, document);

How can this error occur? Should initMyLib be inside the scope of the enclosing (self-envoking) function?

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别挽留 2025-01-02 05:06:03

将 setTimeout("initMyLib()", 50); 更改为 setTimeout(initMyLib, 50);

当您传递一个字符串作为参数时，它会尝试在以下情况下对其求值：超时被触发，但它将在全局范围内运行。并且您的方法不存在于全局范围内。

演示位于 http://jsfiddle.net/gaby/zVr7L/

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时光匆匆的小流年 2025-01-02 05:06:03

您还可以使用真正的匿名函数来避免范围问题：

(function() {
    if(typeof(myLib) == 'undefined')
        setTimeout(arguments.callee, 50);
    else
        // loaded
})()

You could also use a real anonymous function to avoid scoping issues:

(function() {
    if(typeof(myLib) == 'undefined')
        setTimeout(arguments.callee, 50);
    else
        // loaded
})()

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祁梦 2025-01-02 05:06:03

尝试阅读此答案以获取一些线索：递归函数与 setInterval 与 setTimeout javascript

这是该答案的代码示例：

/*
this will obviously crash... and all recursion is at risk of running out of call stack and breaking your page...

function recursion(c){
    c = c || 0;
    console.log(c++);
    recursion(c);
}
recursion();

*/

// add a setTimeout to reset the call stack and it will run "forever" without breaking your page!
// use chrome's heap snapshot tool to prove it to yourself.  :)

function recursion(c){
    setTimeout(function(c){
        c = c || 0;
        console.log(c++);
        recursion(c);
    },0,c);
}

recursion();

// another approach is to use event handlers, but that ultimately uses more code and more resources

Try reading this answer for some clues: recursive function vs setInterval vs setTimeout javascript

This is the code sample from that answer:

/*
this will obviously crash... and all recursion is at risk of running out of call stack and breaking your page...

function recursion(c){
    c = c || 0;
    console.log(c++);
    recursion(c);
}
recursion();

*/

// add a setTimeout to reset the call stack and it will run "forever" without breaking your page!
// use chrome's heap snapshot tool to prove it to yourself.  :)

function recursion(c){
    setTimeout(function(c){
        c = c || 0;
        console.log(c++);
        recursion(c);
    },0,c);
}

recursion();

// another approach is to use event handlers, but that ultimately uses more code and more resources

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