Fat arrow function. Source: http://robcee.net/2013/fat-arrow-functions-in-javascript

fat-arrow.js

var listener = node.addEventListener("click", function(event) {
    let _target = event.target;
    this.handleClick(_target);
}.bind(this));
//Inside we call a local method called handleClick() with the event’s target property. Nothing too exciting.

//With Fat Arrow Functions, that becomes:
var listener = node.addEventListener("click", (event) => {
    let _target = event.target;
    this.handleClick(_target);
});