在回调函数中使用 'this' 而不是 '_this/self/$this' 的简单解决方案

Question

我想在回调函数中去掉 _this/self/$this 辅助变量。我写：

export class someClass {
  someFunction = function( ) {
    this.foo = "bar";
    this.anotherClass.doSomething( this, function( foo ) {
       console.log( this.foo, "/", foo );  // "bar / another bar"
    } );
  }
}

和

export class anotherClass {
   anotherFoo: string = "another bar";

   doSomething( _this, cb ) {
      cb.call( _this, this.anotherFoo );
   }
}

有没有更简单的方法来做到这一点？我想去掉'this'参数。

Answer 1

您可以使用arrow function 来传递回调：

class someClass {
  constructor() {
    this.anotherClass = new anotherClass();
  }

  someFunction() {
    this.foo = "bar";
    this.anotherClass.doSomething(foo => {
      console.log( this.foo, "/", foo );
    });
  }
}

class anotherClass {
  anotherFoo: string = "another bar";

  doSomething(cb) {
    cb(this.anotherFoo);
  }
}

Answer 2

您可以使用Function.prototype.bind修改您的代码

这将允许您将特定上下文绑定到函数。

欲了解更多信息：https://developer.mozilla.org/tr/docs/Web/JavaScript/Reference/Global_Objects/Function/bind

export class someClass {
  someFunction = function( ) {
    this.foo = "bar";
    var callback = function(foo) {
      console.log(this.foo, '/', foo);
    };

    this.anotherClass.doSomething(callback.bind(this));
  }
}

和

export class anotherClass {
  anotherFoo: string = "another bar";

  doSomething(cb) {
    cb(this.anotherFoo);
  }
}