From an array of objects, extract value of a property as array
I have JavaScript object array with the following structure:
objArray = [ { foo: 1, bar: 2}, { foo: 3, bar: 4}, { foo: 5, bar: 6} ];
I want to extract a field from each object, and get an array containing the values, for example field foo
would give array [ 1, 3, 5 ]
.
I can do this with this trivial approach:
function getFields(input, field) {
var output = [];
for (var i=0; i < input.length ; ++i)
output.push(input[i][field]);
return output;
}
var result = getFields(objArray, "foo"); // returns [ 1, 3, 5 ]
Is there a more elegant or idiomatic way to do this, so that a custom utility function would be unnecessary?
Note about suggested duplicate, it covers how to convert a single object to an array.
Here is a shorter way of achieving it:
let result = objArray.map(a => a.foo);
OR
let result = objArray.map(({ foo }) => foo)
You can also check Array.prototype.map()
.
Yes, but it relies on an ES5 feature of JavaScript. This means it will not work in IE8 or older.
var result = objArray.map(function(a) {return a.foo;});
On ES6 compatible JS interpreters you can use an arrow function for brevity:
var result = objArray.map(a => a.foo);
Array.prototype.map documentation