How to access object value with ( ) parentheses in name?

Question

Hi I have an object that I have filled from data in a CSV file.

One of my ids is called "Disk_Usage(MB)"

I try using my object.Disk_Usage(MB) but receive an error because javascript thinks disk usage is a function and that MB is a variable.

I receive a reference error on the console saying MB is not defined.

See [*JavaScript property access: dot notation vs. brackets?*](http://stackoverflow.com/questions/4968406/javascript-property-access-dot-notation-vs-brackets/4968448#4968448). — RobG, Jan 25 '15 at 23:10
Sounds like you haven't read your JavaScript book yet. Why not? — Lightness Races in Orbit, Jan 25 '15 at 23:11
See [ECMAScript 5.1 Section 11.2.1 Property Accessors](http://www.ecma-international.org/ecma-262/5.1/#sec-11.2.1) — Oriol, Jan 25 '15 at 23:15

score 5 · Answer 1 · answered Jan 25 '15 at 23:09

5

Use array/bracket notation:

var propertyValue = yourObject['Disk_Usage(MB)'];

If you're wondering why you need to do this and/or "but my object isn't an array!," I would suggest having a read through the "Working with objects" article over at MDN.

answered Jan 25 '15 at 23:09

Cᴏʀʏ

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score 3 · Answer 2 · answered Jan 25 '15 at 23:09

3

Do this:

object['Disk_Usage(MB)']

Read this

answered Jan 25 '15 at 23:09

alexpods

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score 0 · Answer 3 · answered Jan 25 '15 at 23:13

Although object member access can be performed like this:

var o = { 'abc': 123 };
console.log(o.abc);

it is often more convenient to use array-bracket notation:

console.log(o['abc']);

This is one of those times when you must do so, since your key has characters in it that make it an illegal identifier. You must provide it as a string.

Personally, as a matter of consistency, I try to stick to the array-bracket notation all the time.

Further reading: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects#Objects_and_properties

How to access object value with ( ) parentheses in name?

3 Answers3