Remove blank attributes from an Object in Javascript

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

(Question is similar to this one for Arrays)

Answer

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