Remove blank attributes from an Object in Javascript

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

ES10/ES2019 examples

A simple one-liner (returning a new object).

let o = Object.fromEntries(Object.entries(obj).filter(([_, v]) => v != null)); 

Same as above but written as a function.

function removeEmpty(obj) {   return Object.fromEntries(Object.entries(obj).filter(([_, v]) => v != null)); } 

This function uses recursion to remove items from nested objects.

function removeEmpty(obj) {   return Object.fromEntries(     Object.entries(obj)       .filter(([_, v]) => v != null)       .map(([k, v]) => [k, v === Object(v) ? removeEmpty(v) : v])   ); } 

ES6/ES2015 examples

A simple one-liner. Warning: This mutates the given object instead of returning a new one.

Object.keys(obj).forEach((k) => obj[k] == null && delete obj[k]); 

A single declaration (not mutating the given object).

let o = Object.keys(obj)   .filter((k) => obj[k] != null)   .reduce((a, k) => ({ ...a, [k]: obj[k] }), {}); 

Same as above but written as a function.

function removeEmpty(obj) {   return Object.entries(obj)     .filter(([_, v]) => v != null)     .reduce((acc, [k, v]) => ({ ...acc, [k]: v }), {}); } 

This function uses recursion to remove items from nested objects.

function removeEmpty(obj) {   return Object.entries(obj)     .filter(([_, v]) => v != null)     .reduce(       (acc, [k, v]) => ({ ...acc, [k]: v === Object(v) ? removeEmpty(v) : v }),       {}     ); } 

Same as the function above, but written in an imperative (non-functional) style.

function removeEmpty(obj) {   const newObj = {};   Object.entries(obj).forEach(([k, v]) => {     if (v === Object(v)) {       newObj[k] = removeEmpty(v);     } else if (v != null) {       newObj[k] = obj[k];     }   });   return newObj; } 

ES5/ES2009 examples

In the old days things were a lot more verbose.

This is a non recursive version written in a functional style.

function removeEmpty(obj) {   return Object.keys(obj)     .filter(function (k) {       return obj[k] != null;     })     .reduce(function (acc, k) {       acc[k] = obj[k];       return acc;     }, {}); } 

This is a non recursive version written in an imperative style.

function removeEmpty(obj) {   const newObj = {};   Object.keys(obj).forEach(function (k) {     if (obj[k] && typeof obj[k] === "object") {       newObj[k] = removeEmpty(obj[k]);     } else if (obj[k] != null) {       newObj[k] = obj[k];     }   });   return newObj; } 

And a recursive version written in a functional style.

function removeEmpty(obj) {   return Object.keys(obj)     .filter(function (k) {       return obj[k] != null;     })     .reduce(function (acc, k) {       acc[k] = typeof obj[k] === "object" ? removeEmpty(obj[k]) : obj[k];       return acc;     }, {}); }