Javascript Array of objects get single value

Question

Lets say I have an array of objects:

var employees=[]
employees[0]={name:"George", age:32, retiredate:"March 12, 2014"}
employees[1]={name:"Edward", age:17, retiredate:"June 2, 2023"}
employees[2]={name:"Christine", age:58, retiredate:"December 20, 2036"}
employees[3]={name:"Sarah", age:62, retiredate:"April 30, 2020"}

Is there an array function that will allow me to get one property as an array, for example:

namesArray = employees.reduceToProperty('name'); // none existent function i made up!

// should return ["George","Edward","Christine","Sarah"]

I know how get the desired result with a loop, I am just hoping for an array function or combination of functions exist that can do this in one line.

and http://stackoverflow.com/q/19590865/218196 – Felix Kling Apr 12 '14 at 21:42 — Felix Kling, Apr 12 '14 at 21:42

score 26 · Accepted Answer · edited Mar 23 '23 at 00:18

26

Array.prototype.map can be used to map one array to another.

var names = employees.map(function(i) {
  return i.name;
});

names is now an array containing the name-properties of the objects.

edited Mar 23 '23 at 00:18

asportnoy

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answered Apr 12 '14 at 20:57

phylax

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it was an easy one :) - there are more usefull array functions, take a look: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/prototype – phylax Apr 12 '14 at 21:07
The (cleaner) ES6 sayntax is: `const names = employees.map((i) => i.name)` (Just making [tickietackie's](https://stackoverflow.com/users/9119176/tickietackie) comment to update this old solution more readable) – Cadoiz May 03 '23 at 13:10

score 2 · Answer 2 · answered Apr 12 '14 at 20:58

2

Array.prototype.map maps one array to another:

var names = employees.map(function (val) {
    return val.name;
});
// ['George', 'Edward', 'Christine', 'Sarah']

answered Apr 12 '14 at 20:58

zzzzBov

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I marked this answer as a duplicate to [the accepted answer](https://stackoverflow.com/a/23036033/4575793). That was declined because it was answered only a minute later, but I still think, we don't need the same answer twice. – Cadoiz May 03 '23 at 13:04

Cymen · Answer 3 · 2014-04-12T21:15:59.827

If you find yourself doing this frequently, you might consider using pluck from Underscore/Lo-Dash:

var listOfPropertyNames = _.pluck(list, 'propertyName');

If you don't want to do include a library, it is of course possible to write your own pluck for use on your code base:

function pluck(list, propertyName) {
  return list.map(function(i) {
    return i[propertyName];
  });
}

And running it:

pluck([{name: 'a'}, {name: 'b'}], 'name');
["a", "b"]

You'll have to decide how to handle the edge cases like:

object in the list not having the property
an undefined being in the list
?

Javascript Array of objects get single value

3 Answers3

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