Use a variable inside a dictionary (associative array) in javascript

Question

I have this particular script which uses a javascript dictonary

var z= 'Bingo';
var fruit={ 'Bingo' :1};
var fruit2={ z :1};
alert(fruit[z]);
alert(fruit2[z]);
alert(fruit2['z']);

The first alert gives the expected value 1. However, the second alert gives the alert value as "undefined" and third alert gives the output as 1. Is there a way to use a variable inside a dictionary, ie. can we specify the javascript interpreter to read z as a variable rather than as string 'z'?

Thanks!

This question appears to be off-topic because it is about an extremely basic feature which is covered in the first pages of any tutorial. — , Mar 08 '14 at 02:28

score 2 · Answer 1 · answered Oct 03 '13 at 06:45

2

Yes, you can do this easily, but not inside an object literal. Property names in object literals are taken literally. They are not variable names. JavaScript quotes them implicitly if you don't quote them.

For example, these two object literals are the same:

{ a: 1 }

{ 'a': 1 }

To use a variable, you need to use [] notation outside an object literal:

var z = 'Bingo';
var fruit2 = {};
fruit2[z] = 1;

answered Oct 03 '13 at 06:45

Michael Geary

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Explain how you can't do it inside an object literal please. – bozdoz Oct 03 '13 at 06:46
Actually, I have a huge dictionary which needs to be created. The above method will be a cumbersome job to do, I am looking for an approach if I can use the variable inside the inline definition of the dictionary. – Abhinav Jain Oct 03 '13 at 06:48
1

You can't do that. You have to use `[]` notation if you want to use variable names instead of literal property names. – Michael Geary Oct 03 '13 at 06:49
1

Ah. I understand the question and the answer now. Thanks. +1 – bozdoz Oct 03 '13 at 06:50
@AbhinavJain This approach shouldn't be much more cumbersome. – bozdoz Oct 03 '13 at 06:52
Seems I will have to proceed this way only. Thanks for the help! :) – Abhinav Jain Oct 03 '13 at 06:53

Use a variable inside a dictionary (associative array) in javascript

1 Answers1