如何从角度2的回调函数中调用父函数？

Question

Here is a class

export class ChatDetailPage {

constructor(){

}

funcA(){
     var options = {
        onSubmit: function (text) {
        //i want to be able to access funcB from here 
        this.funcB(text)
          },
this.nativeKeyboard.showMessenger(options)
}

funcB(text){
  alert (text);
}

}

Here in this case how can i call funcB from onsubmit callback function in Anular 2 or Ionic 3.

Thanks in advance.

Answer 1

Use an arrow function, which captures the value of this :

export class ChatDetailPage {

    constructor(){

    }

    funcA(){
       var options = {
           onSubmit: text => {
              //i want to be able to access funcB from here 
              this.funcB(text)
           },
       };
       this.nativeKeyboard.showMessenger(options)
   }

   funcB(text){
      alert (text);
   }
}

Answer 2

Sometimes you won't be able to use an arrow function, fe when it's an inbuilt or library function. The solution you can use in this case is bind the this variable to a variable called self or whatever you want.

funcA(){
     // bind the this variable to 'self' outside of the function scope
     var self = this;
     var options = {
        onSubmit: function (text) {
            // and use self instead of this 
            self.funcB(text)
        },
     this.nativeKeyboard.showMessenger(options)
}

funcB(text){
  alert (text);
}