从javascript中的子类回调访问主类属性答案

【问题标题】：access main class attributes from sub class callback in javascript从javascript中的子类回调访问主类属性
【发布时间】：2017-12-28 23:43:36
【问题描述】：

Javascript 代码我想在媒体回调函数中使用 this.progressbar

  class CatMusicPlayer {

  constructor(url,playPauseBtn,progressbar,progressTime,durationTime) {
    this.url = url;
    this.playPauseBtn = playPauseBtn;
    this.progressbar = progressbar;
    this.progressTime = progressTime;
    this.durationTime = durationTime;

    new Media(url,null,this.logerror,function(mediaStatus){

        /*
            i want to use this.progressbar,
            but in this block "this" reffers to Media class.
            Media is kind of another class similar to CatMusicPlayer
        */

    });
  }

【问题讨论】：

标签： javascript class object

【解决方案1】：

将this 的值缓存到另一个变量，例如const _thisMP = this; 稍后使用它_thisMP.progressbar();

或者在您的情况下，您甚至可以直接调用progressbar()，因为它可以访问

class CatMusicPlayer {

  constructor(url,playPauseBtn,progressbar,progressTime,durationTime) {
    this.url = url;
    this.playPauseBtn = playPauseBtn;
    this.progressbar = progressbar;
    this.progressTime = progressTime;
    this.durationTime = durationTime;
    const _thisMP = this;

    new Media(url,null,this.logerror,function(mediaStatus){
       _thisMP.progressbar(); // call here

        /*
            i want to use this.progressbar,
            but in this block "this" reffers to Media class.
            Media is kind of another class similar to CatMusicPlayer
        */

    });
  }

【讨论】：

谢谢你:)。这很简单。我刚刚陷入寻找其他出路的循环。谢谢 :) 现在可以正常使用了
@KathanShah 很高兴它有帮助。

【解决方案2】：

class CatMusicPlayer {

  constructor(url,playPauseBtn,progressbar,progressTime,durationTime) {
    this.url = url;
    this.playPauseBtn = playPauseBtn;
    this.progressbar = progressbar;
    this.progressTime = progressTime;
    this.durationTime = durationTime;
    let self = this;
    new Media(url,null,this.logerror,function(mediaStatus){
       self.progressbar();


    });
  }

【讨论】：