Filter Object in Javascript
Published in
2 min readFeb 8, 2022
In Javascript, There are many ways to filter the Object.
- Using reduce & Object.keys
- Using reduce, Object.keys & Object.assign
- Using map & spread syntax instead of reduce
- Using Object.entries & Object.fromEntries
- Using lodash.js
Using reduce & Object.keys
Object.filter = (obj, predicate) =>
Object.keys(obj)
.filter( key => predicate(obj[key]) )
.reduce( (res, key) => (res[key] = obj[key], res), {} );
// Example use:
var scores = {
John: 2, Sarah: 3, Janet: 1
};
var filtered = Object.filter(scores, score => score > 1);
console.log(filtered);
Using reduce, Object.keys & Object.assign
Object.filter = (obj, predicate) =>
Object.keys(obj)
.filter( key => predicate(obj[key]) )
.reduce( (res, key) => Object.assign(res, { [key]: obj[key] }), {} );
// Example use:
var scores = {
John: 2, Sarah: 3, Janet: 1
};
var filtered = Object.filter(scores, score => score > 1);
console.log(filtered);
Using map & spread syntax instead of reduce
Object.filter = (obj, predicate) =>
Object.assign(...Object.keys(obj)
.filter( key => predicate(obj[key]) )
.map( key => ({ [key]: obj[key] }) ) );
// Example use:
var scores = {
John: 2, Sarah: 3, Janet: 1
};
var filtered = Object.filter(scores, score => score > 1);
console.log(filtered);
Using Object.entries & Object.fromEntries
Object.filter = (obj, predicate) =>
Object.fromEntries(Object.entries(obj).filter(predicate));
// Example use:
var scores = {
John: 2, Sarah: 3, Janet: 1
};
var filtered = Object.filter(scores, ([name, score]) => score > 1);
Using Lodash.js
_.pick({name: 'moe', age: 50, userid: 'moe1'}, 'name', 'age');