arrow-functions

I'm using arrow functions and I'm debugging with Chrome and Firefox Dev Tool. I am getting, this as undefined, even though the code still works. My assumption is, that it has something to do with source-maps. Here are the tools I use in order to build the my code: webpack (devtool: eval) babel-loader (es5 preset) typescript-loader The problem is that the chrome debugger believes that the this in the source code refers to the rune-time this , but this inside a arrow function in typescript source code is actually transformed to _this , so it's showing you the wrong object. This is why it's only

The fat arrow can be used in different settings but it somehow doesn't always bind to the instance I want. The fat arrow binds at 3 occasions when declaring a method when declaring a function within a method when declaring a function in global context 1. When declaring a method When the Coffeescript compiler encouters the following syntactical pattern within a class declaration class A somemethod: (paramlist) => This will yield the following code within the constructor of class A this.somemethod = __bind(this.somemethod, this); That is the definition for that instance is overwriting the

I started to use ES6 fat arrow function notation and I really like it. But I am a little bit confused about it context. As far as I know, keyword this inside fat arrow function refers to context where the function is currently running. I wanted to do some simple jQuery iteration like: $('ul#mylist > li').each(() => { $(this).addClass('some-class-name'); }); But obviously this piece of code not working. How do I refer, inside fat arrow function, to current "LI" element in this specific code? The each() method supplies two parameters to the callback-function. They are current index and the

I am using ReactJS with Babel and Webpack and using ES6 as well as the proposed class fields for arrow functions. I understand that arrow functions make things more efficient by not recreating the functions each render similar to how binding in the constructor works. However, I am not 100% sure if I am using them correctly. The following is a simplified section of my code in three different files. My code: Main.js prevItem = () => { console.log("Div is clicked") } render(){ return ( <SecondClass prevItem={this.prevItem} /> ) } SecondClass.js <ThirdClass type="prev" onClick={()=>this.props

When building a class in CoffeeScript, should all the instance method be defined using the => ("fat arrow") operator and all the static methods being defined using the -> operator? No, that's not the rule I would use. The major use-case I've found for the fat-arrow in defining methods is when you want to use a method as a callback and that method references instance fields: class A constructor: (@msg) -> thin: -> alert @msg fat: => alert @msg x = new A("yo") x.thin() #alerts "yo" x.fat() #alerts "yo" fn = (callback) -> callback() fn(x.thin) #alerts "undefined" fn(x.fat) #alerts "yo" fn(-> x

This question already has an answer here: Are 'Arrow Functions' and 'Functions' equivalent / exchangeable? 1 answer Methods in ES6 objects: using arrow functions 4 answers I'm trying to figure out why an arrow function in an object literal is called with window as this . Can someone give me some insight? var arrowObject = { name: 'arrowObject', printName: () => { console.log(this); } }; // Prints: Window {external: Object, chrome: Object ...} arrowObject.printName(); And an object that works as expected: var functionObject = { name: 'functionObject', printName: function() { console.log(this);

Is there an elegant way to tell Harmony's slim arrow functions apart from regular functions and built-in functions? The Harmony wiki states that: Arrow functions are like built-in functions in that both lack .prototype and any [[Construct]] internal method. So new (() => {}) throws a TypeError but otherwise arrows are like functions Which means, you can test for arrow functions like: !(()=>{}).hasOwnProperty("prototype") // true !(function(){}).hasOwnProperty("prototype") // false But the test will also return true for any built-in function, e.g. setTimeout or Math.min . It sort of works in