Javascript (JS) useful functions
Get unique values from an array
let newArr = [...new Set([1, 2, 3, 3])] // => [1,2,3]
Remove falsy values from array
let newArr = [0, undefined, null, false, true, 'myval'].filter(Boolean) // => [true, 'myval]
Merge objects
let location = { language: 'English', country: 'Singapore' } let personalInfo = { name: 'LV', age: 30 } let merged = {...location, ...personalInfo } // =>{"language":"English","country":"Singapore","name":"LV","age":30}
Three dots
Common usage:
const names = ["Hai", "Son", "Linh"] const [firstName, ...restNames] = names; console.log(firstName); // Hai console.log(restNames); // ["Son", "Linh"]
const info = { name: "LV", age: "21", gender: "male" } const { name, ...restThings } = info; // console.log(name) => "LV" // console.log(restThings) => {"age":"21","gender":"male"}
const names = ["LV", "Jack"]; const newArr = ["Antony", ...names]; //["Antony", "LV", "Jack"]
const blog = { blog1: "need_replaced" blog2: "medium", blog3: "reddit" } const extended = { ...blog, blog1: "anonystick", }; // { blog1: "anonystick", blog2: "medium", blog3: "reddit" }
Get arguments
function myFunc(name, ...rest) { console.log(name); // 'LV' console.log(rest); // ["Kevin", "Jack"] } myFunc("LV", "Kevin", "Jack");
Create date time object
const dateFields = [1970, 0, 1]; // 1 Jan 1970 const d = new Date(...dateFields);