Y a-t-il une fonction standard pour vérifier les variables null, undefined ou blank dans JavaScript

96

if( value ) { } 

if( typeof foo !== 'undefined' ) {     // foo could get resolved and it's defined } 

90

return value === undefined || value === null; 

return value == null; // also returns true if value is undefined 

72

function isEmpty(value){   return (value == null || value.length === 0); } 

undefined  // Because undefined == null  null  []  "" 

function isEmpty(value){   return (value == null || value === ''); } 

69

if (typeof value !== 'undefined' && value) {     //deal with value' }; 

51

function typeOf(obj) {   return {}.toString.call(obj).split(' ')[1].slice(0, -1).toLowerCase(); } 

function typeOf(obj) {   const { toString } = Object.prototype;   const stringified = obj::toString();   const type = stringified.split(' ')[1].slice(0, -1);    return type.toLowerCase(); } 

typeOf(); //undefined typeOf(null); //null typeOf(NaN); //number typeOf(5); //number typeOf({}); //object typeOf([]); //array typeOf(''); //string typeOf(function () {}); //function typeOf(/a/) //regexp typeOf(new Date()) //date typeOf(new WeakMap()) //weakmap typeOf(new Map()) //map