Javascript - removing undefined fields from an object [duplicate]

Answer 1

One could also use the JQuery filter for objects

var newobj = $(obj).filter(function(key) {
    return $(this)[key]!== undefined;
  })[0];

Demo here

Answer 2

This one is easy to remember, but might be slow. Use jQuery to copy non-null properties to an empty object. No deep copy unless you add true as first argument.

myObj = $.extend({}, myObj);

Answer 3

Because it doesn't seem to have been mentioned, here's my preferred method, sans side effects or external dependencies:

const obj = {
  a: 1,
  b: undefined
}

const newObject = Object.keys(obj).reduce((acc, key) => {
  const _acc = acc;
  if (obj[key] !== undefined) _acc[key] = obj[key];
  return _acc;
}, {})

console.log(newObject)
// Object {a: 1}

Answer 4

I prefer to use something like Lodash:

import { pickBy, identity } from 'lodash'

const cleanedObject = pickBy(originalObject, identity)

Note that the identity function is just x => x and its result will be false for all falsy values. So this removes undefined, "", 0, null, ...

If you only want the undefined values removed you can do this:

const cleanedObject = pickBy(originalObject, v => v !== undefined)

It gives you a new object, which is usually preferable over mutating the original object like some of the other answers suggest.