没有本地功能微观优化？ [英] Is not having local functions a micro optimisation?

问题描述

将内部函数移到这个函数之外，以便每次调用函数时都不会创建它是微优化吗？

Would moving the inner function outside of this one so that its not created everytime the function is called be a micro-optimisation?

在这种特殊情况下，<$> c $ c> doMoreStuff 函数仅在 doStuff 中使用。我是否应该担心像这样的本地函数？

In this particular case the doMoreStuff function is only used inside doStuff. Should I worry about having local functions like these?

function doStuff() {
    var doMoreStuff = function(val) {
         // do some stuff
    }

    // do something
    for (var i = 0; i < list.length; i++) {
         doMoreStuff(list[i]);
         for (var  j = 0; j < list[i].children.length; j++) {
              doMoreStuff(list[i].children[j]);
         }
    }
    // do some other stuff

}

一个例子就是说：

function sendDataToServer(data) {
    var callback = function(incoming) {
         // handle incoming
    }

    ajaxCall("url", data, callback);

} 

推荐答案

不确定如果属于微优化类别。我会说不。

Not sure if this falls under the category "micro-optimization". I would say no.

但这取决于您拨打 doStuff 的频率。如果你经常调用它，那么一遍又一遍地创建函数是不必要的，肯定会增加开销。

But it depends on how often you call doStuff. If you call it often, then creating the function over and over again is just unnecessary and will definitely add overhead.

如果你不想拥有辅助函数 在全局范围内，但避免重新创建它，你可以像这样包装它：

If you don't want to have the "helper function" in global scope but avoid recreating it, you can wrap it like so:

var doStuff = (function() {
    var doMoreStuff = function(val) {
         // do some stuff
    }
    return function() {
        // do something
        for (var i = 0; i < list.length; i++) {
            doMoreStuff(list[i]);
        }
        // do some other stuff 
    }
}());

由于返回的函数是一个闭包，它可以访问 doMoreStuff 。请注意，外部函数立即执行（（function（）{...}（）））。

As the function which is returned is a closure, it has access to doMoreStuff. Note that the outer function is immediately executed ( (function(){...}()) ).

或者您创建一个包含函数引用的对象：

Or you create an object that holds references to the functions:

var stuff = {
    doMoreStuff: function() {...},
    doStuff: function() {...}
};

---

有关封装，对象创建模式和其他的更多信息概念可以在 JavaScript这本书中找到模式 。

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