How to call a component function from inside a callback for angular 2 + (razorpay)?

Question

So I am trying to call a function from within a callback response on an api for a payment app razorpay. I cannot use 'this' to call functions within the component as it is within a nested function in the handler. How can I call the function handle_response() from the callback "handler"?

myComponent.ts

var options = {
    "amount": 100, 
    "name": "ABC",
    "currency": "USD",
    "handler": function (response){
        console.log(response);//this returns the expected value
        this.handle_response(response); //does not work as cannot identify 'this'
    }
};
var rzp1 = new this.winRef.nativeWindow.Razorpay(options);
rzp1.open();

handle_response(_response){....}

Answer 1

You want to use the bind method of your function or the fat arrow syntax from typescript. It would be either:

let options = {
    "amount": 100, 
    "name": "ABC",
    "currency": "USD",
    "handler": function (response){
        console.log(response);//this returns the expected value
        this.handle_response(response); //does not work as cannot identify 'this'
    }.bind(this)
};
let rzp1 = new this.winRef.nativeWindow.Razorpay(options);
rzp1.open();

handle_response(_response){....}

OR you can use javascript arrow function. read more about arrow function here

let options = {
    "amount": 100, 
    "name": "ABC",
    "currency": "USD",
    "handler": (response) => {
        console.log(response);//this returns the expected value
        this.handle_response(response); //does not work as cannot identify 'this'
    }
};
let rzp1 = new this.winRef.nativeWindow.Razorpay(options);
rzp1.open();

handle_response(_response){....}