Question

How do I remove all attributes which are undefined or null in a JavaScript object?

(Question is similar to this one for Arrays)

Answer 1

You can loop through the object:

var test = {   test1: null,   test2: 'somestring',   test3: 3, }  function clean(obj) {   for (var propName in obj) {     if (obj[propName] === null || obj[propName] === undefined) {       delete obj[propName];     }   }   return obj }  console.log(test); console.log(clean(test));

If you’re concerned about this property removal not running up object’s proptype chain, you can also:

function clean(obj) {   var propNames = Object.getOwnPropertyNames(obj);   for (var i = 0; i < propNames.length; i++) {     var propName = propNames[i];     if (obj[propName] === null || obj[propName] === undefined) {       delete obj[propName];     }   } } 

A few notes on null vs undefined:

test.test1 === null; // true test.test1 == null; // true  test.notaprop === null; // false test.notaprop == null; // true  test.notaprop === undefined; // true test.notaprop == undefined; // true