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

问题描述

将 this 上下文传递给匿名 forEach 函数的现代正确方法是什么?

What's the modern and correct way to pass the this context to an anonymous forEach function?

function Chart() {

  this.draw = function(data) {
     data.forEach(function(value) {
       //do something with values
       console.log(this); //question: how to get Chart instead of global scope?
     )};
  });

};

推荐答案

将当前的this存储在Chart中的其他变量中

Store the current this in some other variable in Chart like this

function Chart() {
    var self = this;
    this.draw = function(data) {
        data.forEach(function(value) {
            //do something with values
            console.log(self);
        });
    }
};

此外，您可以像下面这样传递this，如Array.prototype.forEach 接受 this

Also, you can pass the this like the following, as Array.prototype.forEach accepts this

arr.forEach(callback[, thisArg])

例如

this.draw = function(data) {
    data.forEach(function(value) {
        //do something with values
        console.log(this);
    }, this); // Pass the current object as the second parameter
}

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