理解Javascript中的链接方法 [英] Understanding Methods Chaining in Javascript

问题描述

我是ES6和Javascript的新手，我无法弄清楚在下面这段代码中链接这个dump（）方法有什么问题。

I'm new to ES6 and Javascript and I can't figure out what's wrong with chaining this dump() method in the following piece of code.

它返回 main.js：25未捕获的TypeError：无法读取未定义的属性'dump'：

class TaskCollection {

constructor(tasks = []) {
    this.tasks = tasks;
}

addTasks(newTasks = []) {
    this.tasks = this.tasks.concat(newTasks);
}

dump() {
    console.log(this.tasks);
}

}

let myTasks = new TaskCollection([
        'Do stuff'
]);

myTasks.addTasks([
    'New Task'
]).dump();

现在如果我不链接那个dump（）方法，一切都会正常工作。

Now if I don't chain that dump() method, everything would work just fine.

myTasks.addTasks([
'New Task'
]);

myTasks.dump();

推荐答案

方法 addTasks 未返回对象的引用。如果你想链接工作，你的方法需要如下所示：

Method addTasks is not returning a reference to the object. If you want chaining to work, your method needs to look like this:

addTasks(newTasks = []) {
    this.tasks = this.tasks.concat(newTasks);

    return this;
}

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