ecmascript-harmony

I went trough ES6 features and Generators caught my eye. One thing that sprang to mind is chaining Promise objects, that I could not do with loops. What other mechanics we will be able to do, that we could not before? I do understand this is broad question, still I can't think of anything but Promises at the moment. By using yield , generators can be suspended at any point in the control flow of your function, saving your current state of execution (scope & stack). Without generators, this is more complicated: you need to explicitly keep track of the state branching and (especially) looping

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

The typical way to loop x times in JavaScript is: for (var i = 0; i < x; i++) doStuff(i); But I don't want to use the ++ operator or have any mutable variables at all. So is there a way, in ES6, to loop x times another way? I love Ruby's mechanism: x.times do |i| do_stuff(i) end Anything similar in JavaScript/ES6? I could kind of cheat and make my own generator: function* times(x) { for (var i = 0; i < x; i++) yield i; } for (var i of times(5)) { console.log(i); } Of course I'm still using i++ . At least it's out of sight :), but I'm hoping there's a better mechanism in ES6. OK! The code below

As you know, there is a proposal for a shortcut for .bind() function, so you can write: ::this.handleStuff and it will work like that in es5: this.handleStuff.bind(this) My question is: will it be possible to pass arguments this way? I mean a way of writing this with the aforementioned shortcut: this.handleStuff.bind(this, 'stuff') It's a pretty common pattern in React, so it would be nice to shorten it a little. Bergi No. The bind operator ( spec proposal ) comes in two flavours: Method extraction ::obj.method ≡ obj.method.bind(obj) "virtual method" calls obj::function ≡ function.bind(obj)