Javascript: Get all objects by specific field

Question

This might be a quite easy question, but I haven't encountered an elegant solution.

How do you get all objects from an array by a single field. For example;


var users = [{name:'John', age: 20}, 
{name:'Sarah', age: 21}, 
{name:'George', age:34}];
var names = magicFunction(users, 'name');
// names = ['John', 'Sarah', 'George']; 
// Another challenge is not to get field name (in this case 'name') with the value

I wonder if you could do it with functions like filter or map, without writing a long function?

p.s.w.g · Accepted Answer · 2019-02-25 14:45:39Z

2

Yes, it's pretty straight forward:

var prop = 'name';
var names = users.map(function(x) { return x[prop]; });

Or if you want to write this into a function:

function getProp(arr, prop)
{
    return arr.map(function(x) { return x[prop]; });
}

var names = getProp(users, 'name');

Update In ES6 syntax:

const getProp = (arr, prop) => Array.prototype.map.call(arr, x => x[prop]);
const names = getProp(users, 'name');

edited Feb 25, 2019 at 14:45

answered May 16, 2014 at 20:44

p.s.w.g

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Explosion Pills · Accepted Answer · 2014-05-16 20:44:08Z

1

Underscore.js (which you can install as a node package) has a function called _.pluck which does exactly this. If you _ = require("underscore") you can actually replace magicFunction with _.pluck.

answered May 16, 2014 at 20:44

Explosion Pills

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Florian Margaine · Accepted Answer · 2014-05-16 20:48:40Z

0

@p.s.w.g is probably the solution you're looking for, but I'd like to show another one: using core.operators.

var names = users.map(opts.get('name'));

answered May 16, 2014 at 20:48

Florian Margaine

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