如何将上下文传递给匿名函数？ [英] How to pass context to anonymous function?

问题描述

有一些功能，它可以做很长时间的工作，并提供回调。

There are some function, thats do something long work and its provides callback.

someFunc: function(argument, callback, context) {
  // do something long

  // call callback function
  callback(context);
}

在申请中我使用此功能

someFunc('bla-bla', function (context) {
  // do something with this scope
  context.anotherFunc();
}, this);

如何在不传递上下文的情况下实现回调函数参数？

需要这样的：

someFunc('bla-bla', function () {
  // do something with this scope
  this.anotherFunc();
}, this);

推荐答案

接受的答案似乎有点过时了。假设您在相对较新的浏览器上运行，可以在 Function.prototype.bind US / docs / Web / JavaScript / Reference / Global_Objects / Function / bindrel =noreferrer> vanilla javascript 。或者，如果您使用下划线或 jQuery ，你可以使用 _。bind 或 $。proxy 分别（如果需要，将回退到致电 / 申请）。

The accepted answer seems somewhat outdated. Assuming you're operating on a relatively modern browser, you can use Function.prototype.bind in vanilla javascript. Alternatively, if you are using underscore or jQuery, you can use _.bind or $.proxy respectively (which will fallback to call/apply if necessary).

以下是这三个选项的简单演示：

Here is a simple demonstration of these three options:

// simple function that takes another function
// as its parameter and then executes it.
function execute_param(func) {
    func();
}

// dummy object. providing an alternative context.
obj = {};
obj.data = 10;

// no context provided
// outputs 'Window'
execute_param(function(){
    console.log(this);
});

// context provided by js - Function.prototype.bind
// src: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind
// outputs 'Object { data=10 }''
execute_param(function(){
    console.log(this);
}.bind(obj));

// context provided by underscore - _.bind
// src: http://underscorejs.org/#bind
// outputs 'Object { data=10 }'
execute_param(_.bind(function(){
    console.log(this);
},obj));

// context provided by jQuery - $.proxy
// src: http://api.jquery.com/jQuery.proxy/
// outputs 'Object { data=10 }'
execute_param($.proxy(function(){
    console.log(this);
},obj));

您可以在这里找到jsfiddle中的代码： http://jsfiddle.net/yMm6t/1/ （注意：确保开发者控制台已打开，否则您将看不到任何内容输出）

You can find the code in a jsfiddle here: http://jsfiddle.net/yMm6t/1/ (note: ensure that the developer console is open, or you won't see any output)

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