Revisions to How do I loop through or enumerate a JavaScript object?

Add combined version with Object.entries, for-of, and destructuring.

edited May 15, 2019 at 17:17

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Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ECMAScript 6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ECMAScript 8 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

You can combine for...of, destructuring, and Object.entries:

for (const [key, value] of Object.entries(obj)) { console.log(key, value); }

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ECMAScript 6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ECMAScript 8 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ECMAScript 6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ECMAScript 8 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

You can combine for...of, destructuring, and Object.entries:

for (const [key, value] of Object.entries(obj)) { console.log(key, value); }

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Political view on their new unfavoured naming convention

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edit approved Nov 19, 2018 at 3:54

Ricky Boyce

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Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ES6ECMAScript 6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ES2017ECMAScript 8 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Edit: ES2016 → ES6

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ES6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ES2017 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Edit: ES2016 → ES6

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ECMAScript 6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ECMAScript 8 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

deleted 3 characters in body

Source Link

edited May 8, 2018 at 18:51

Axel Rauschmayer

25.8k
5
26
17

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ES2016ES6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ES2017 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Edit: ES2016 → ES6

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ES2016 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ES2017 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Under ECMAScript 5, you can combine Object.keys() and Array.prototype.forEach():

var obj = { first: "John", last: "Doe" }; Object.keys(obj).forEach(function(key) { console.log(key, obj[key]); });

ES6 adds for...of:

for (const key of Object.keys(obj)) { console.log(key, obj[key]); }

ES2017 adds Object.entries() which avoids having to look up each value in the original object:

Object.entries(obj).forEach( ([key, value]) => console.log(key, value) );

Both Object.keys() and Object.entries() iterate properties in the same order as a for...in loop but ignore the prototype chain. Only the object's own enumerable properties are iterated.

Edit: ES2016 → ES6