Javascript 1.7 added destructuring assignment which allows you to do essentially what you are after. function getTuple(){ return [“Bob”, 24]; } var [a, b] = getTuple(); // a === “bob” , b === 24 are both true
Yes, you just have to provide a default value for the complete argument: function myFunction({option1 = true, option2 = ‘whatever’} = {}) { // ^^^^ console.log(option1, option2); // do something… }
child: { title2 } is just destructuring the child property. If you want to pick up the child property itself simply specify it in the statement: let { title, child, child: { title2 } } = obj1; const obj1 = { title: ‘foo’, child: { title2: ‘bar’ } } let { title, child, child: { … Read more
The two pieces of code are equivalent but the first one is using the ES6 destructuring assignment to be shorter. Here is a quick example of how it works: const obj = { name: “Fred”, age: 42, id: 1 } //simple destructuring const { name } = obj; console.log(“name”, name); //assigning multiple variables at one … Read more
Destucturing is using structure-like syntax on the left-hand-side of an assignment to assign elements of a structure on the right-hand-side to individual variables. For exampple, let array = [1, 2, 3, 4]; let [first, _, third] = array; destructures the array [1, 2, 3] and assigns individual elements to first and third (_ being a … Read more
If you use it, and call the function with no parameters, it works: function drawES6Chart({size=”big”, cords = { x: 0, y: 0 }, radius = 25} = {}) { console.log(size, cords, radius); // do some chart drawing } drawES6Chart(); if not, an error is thrown: TypeError: can’t convert undefined to object function drawES6Chart({size=”big”, cords = … Read more
You can assign it a valid variable name using this syntax: var {“my name”: myName, age} = obj2; // use myName here
Can I avoid declaring a useless variable when array destructuring when I am only interested in array values beyond index 0? Yes, if you leave the first index of your assignment empty, nothing will be assigned. This behavior is explained here. // The first value in array will not be assigned const [, b, …rest] … Read more
First off, var [a, b] = f() works just fine in JavaScript 1.7 – try it! Second, you can smooth out the usage syntax slightly using with(): var array = [1,2]; with (assign(array, { var1: null, var2: null })) { var1; // == 1 var2; // == 2 } Of course, this won’t allow you … Read more
import {Link} from ‘react-router’; imports a named export from react-router, i.e. something like export const Link = 42; import Router from ‘react-router’; const {Link} = Router; pulls out the property Link from the default export, assuming it is an object, e.g. export default { Link: 42 }; (the default export is actually nothing but a … Read more