I have been playing with ES6 for a while and I noticed that while variables declared with var are hoisted as expected...  console.log(typeof name); // undefined var name = "John";   ...variables declared with let or const seem to have some...
I've heard that accessing let and const values before they are initialized can cause a ReferenceError because of something called the temporal dead zone.  What is the temporal dead zone, how does it relate to scope and hoisting, and in what sit...
In JavaScript, var declarations create properties on the global object:  var x = 15; console.log(window.x); // logs 15 in browser console.log(global.x); // logs 15 in Node.js   ES6 introduces lexical scoping with let declarations that have block sc...
Regardless of functional differences, does using the new keywords 'let' and 'const' have any generalized or specific impact on performance relative to 'var'?  After running the program:  function timeit(f, N, S) {     var star...
I've attached an animated gif to illustrate this weird behavior. Essentially, my question is does Chrome console treat var and let differently when used in the same scope? You'll notice that after declaring / assigning a variable, if you try...
I am trying some example in ECMAScript 6. That is working differently compared to other browsers. This returns true in Firefox, but it returns false in IE. Why is this working different in Internet Explorer?  let callbacks = [] for (let i = 0; i <...
I have read where the 'let' keyword is working now in Firefox, and that the use of specifying the version in the script tag is no longer necessary. HOWEVER, despite adding strict mode, I am still getting the Firefox error:    I'd tried bl...
let doesnt't work in some browsers.  Not in their interpeters/ web consoles either.  Why?  (originally I thought there was an inconsistency b/t the browser interpeter and the jsFiddle, but it turns out not to be true, just bad tests on my part.)...

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