Question

我正在尝试在一个开关内设置一个setTimeout，它位于一个foreach内部，位于一个函数内...

TypeError：undefined不是对象（评估'this.Data'）

我试过了

import { DataProvider } from '../xml-provider';
constructor(private Data: DataProvider) { }
items = this.Data.xmldata['step'];  //XML turned into array using 

initiateStepActions(){
    var actionsToTake = this.items[this.currentStep]['timed_actions'];
    if (actionsToTake){
        this.items[this.currentStep]['timed_actions'][0]['action'].forEach(function(foundAction){
          switch (type) {
            case 'customerchat':
              var MesgObject = {text : foundAction['_']};
              //setTimeout(() => {this.Data.broadcastCustomerChatMesg(MesgObject)}, Number(foundAction['$']['showAtSecond']));
              //setTimeout (() => this.Data.broadcastCustomerChatMesg(MesgObject), Number(foundAction['$']['showAtSecond']));
              //setTimeout ( (this.Data.broadcastCustomerChatMesg(MesgObject)).bind(this), Number(foundAction['$']['showAtSecond']));
              //setTimeout (this.Data.broadcastCustomerChatMesg(MesgObject), Number(foundAction['$']['showAtSecond']));
              setTimeout (function(this) { this.Data.broadcastCustomerChatMesg(MesgObject)}, Number(foundAction['$']['showAtSecond']));

              TypeError: undefined is not an object (evaluating 'this.Data.broadcastCustomerChatMesg')
              break;

            case 'supportchat':
              console.log('send a support chat message ');
              break;

            default:
              console.log('defaulted');
          } //end switch
    });// end foreach
  }
}

所有这些都得到了未定义的错误。

Answer 1

写作时

.forEach(function(foundAction){

this不再引用您的类，而是匿名函数。你应该使用箭头功能

.forEach(fundAction => {

并在setTimeout中执行相同操作，以避免传递this的引用。

angular 2 settimeout这是未定义的

1 个答案: