javascript - Why is myVar undefined? -

when socket event drawmouse & draw() function called myvar undefined. why can't access this.myvar within socket.on callback?

import { component, oninit } '@angular/core';  import * io 'socket.io-client';   @component({   selector: 'app-test',   templateurl: './test.component.html',   styleurls: ['./test.component.css'] }) export class testcomponent implements oninit {   myvar:string;    constructor(){     this.socket = io("http://localhost:4300");     this.myvar = "hello"    }    ngoninit() {       this.socket.on('drawmouse', function(data){           this.draw(data)       })   }    draw(){     //this variable undefined     console.log(this.myvar);   } } 

because this inside socket callback not refering component.

try:

 this.socket.on('drawmouse', (data)=>{           this.draw(data)       })