Octal literals are not allowed because disallowing them discourages programmers from using leading zeros as padding in a script. For example, look at the following snippet: var eight = 0008, nine = 00009, ten = 000010, eleven = 011; console.log(eight, nine, ten, eleven); Seems harmless enough, right? We programmers with OCD just want to align … Read more
The language reference uses abstract terms because JavaScript environments can vary widely. In the browser, a window (a frame, a window opened with window.open(), or just a plain browser tab) is a realm. A web worker is a different kind of realm than a window, but it’s a realm. Same goes for service workers. It’s … Read more
That is not actually a babel issue, you are just trying to run CommonJS code (transpiled from ES6 export) in the browser without preparation. CommonJS doesn’t run on the browser, you need to use a tool to package it for the browser, such as Webpack or Browserify. Just by coincidence this week I created a … Read more
Internal properties define the behavior of code as it executes but are not accessible via code. ECMAScript defines many internal properties for objects in JavaScript. Internal properties are indicated by double-square-bracket notation. For example, JavaScript function is an object and it has [[call]] property. [[call]] property is unique to function. Another internal property example is … Read more
There are several things that you can’t emulate from the ECMAScript 5 Object.create method on an ECMAScript 3 environment. As you saw, the properties argument will give you problems since in E3-based implementations there is no way to change the property attributes. The Object.defineProperty method as @Raynos mentioned, works on IE8, but partially, it can … Read more
There are so many answers around there but people always get confused. I know this because I got confused once a while ago. After some time, I grasped the concepts. Bind object/function manually in order to play with state or props inside the function and to avoid scope-related issues Not exactly true. You don’t need … Read more
Regardless of the problem, ActionScript and JavaScript should always yield the same results, as they both implement ECMAScript (or a superset thereof, but for regular expressions they should not disagree). But yes, this will be happening in any language (or rather any regex flavor). The reason is that you are repeating the capturing group. Let’s … Read more
Partial Application You can do partial application: // This lets us call the slice method as a function // on an array-like object. var slice = Function.prototype.call.bind(Array.prototype.slice); function partial(f/*, …args */) { if (typeof f != ‘function’) throw new TypeError(‘Function expected’); var args = slice(arguments, 1); return function(/* …moreArgs */) { return f.apply(this, args.concat(slice(arguments))); }; … Read more
The delete statement is still allowed in strict mode, but some particular uses of it are erroneous. It’s only allowed for object properties, not simple names, and only for object properties that can be deleted. Thus var a = {x: 0}; delete a.x; is fine, but delete Object.prototype; is not, and neither is delete a; … Read more
No, you can’t disable strict mode per function. It’s important to understand that strict mode works lexically; meaning — it affects function declaration, not execution. Any function declared within strict code becomes a strict function itself. But not any function called from within strict code is necessarily strict: (function(sloppy) { “use strict”; function strict() { … Read more