What I don’t understand is how this relates to destructuring. Within removeBreakpoint, you can use url, line, and column directly. The destructuring happens when removeBreakpoint is called with an options object; that object’s matching properties are destructured into individual arguments. Is the idea that you permit the ability to pass an object into this function … Read more
if no such option exists, then maybe there is a nice idiomatic one-liner for doing that ? like, using for…of, or similar ? Indeed, there are several ways to convert a Set to an Array: Using Array.from: Note: safer for TypeScript. const array = Array.from(mySet); Simply spreading the Set out in an array: Note: Spreading … Read more
From the Arrow functions examples, (() => “foobar”)() // returns “foobar” So, the function invocation operator should be outside. (() => { //… })(); Sample: http://www.es6fiddle.net/hsb8s1sj/
Believe it or not… Testing for presence of “=>” in string representation of a function is likely the most reliable way (but not 100%). Obviously we can’t test against either of 2 conditions you mentioned — lack of prototype property and lack of [[Construct]] as that might give false positives with either host objects or … Read more
Using the ES2015 Spread operator: […Array(n)].map() const res = […Array(10)].map((_, i) => { return i * 10; }); // as a one liner const res = […Array(10)].map((_, i) => i * 10); Or if you don’t need the result: […Array(10)].forEach((_, i) => { console.log(i); }); // as a one liner […Array(10)].forEach((_, i) => console.log(i)); Or … Read more
If you use Babel you can use the following syntax to copy property b from x into variable b and then copy rest of properties into variable y: let x = {a: 1, b: 2, c: 3, z:26}; let {b, …y} = x; and it will be transpiled into: “use strict”; function _objectWithoutProperties(obj, keys) { … Read more
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) obj::function(…) ≡ function.call(obj, …) Neither of them feature partial application. For what you want, you should use an arrow function: (…args) => this.handleStuff(‘stuff’, …args) ≡ this.handleStuff.bind(this, ‘stuff’)
The original motivation for introducing symbols to Javascript was to enable private properties. Unfortunately, they ended up being severely downgraded. They are no longer private, since you can find them via reflection, for example, using Object.getOwnPropertySymbols or proxies. They are now known as unique symbols and their only intended use is to avoid name clashes … Read more
Update 3/2022 There is currently a proposal to add Records and Tuples (basically immutable Objects and Arrays) to Javascript. In that proposal, it offers direct comparison of Records and Tuples using === or !== where it compares values, not just object references AND relevant to this answer both Set and Map objects would use the … Read more
A while ago our team migrated all its code (a mid-sized AngularJS app) to JavaScript compiled using Traceur Babel. I’m now using the following rule of thumb for functions in ES6 and beyond: Use function in the global scope and for Object.prototype properties. Use class for object constructors. Use => everywhere else. Why use arrow … Read more