How to access key itself using javascript

Question

I have a JSON like:

  var xx = {'name':'alx','age':12};

Now I can read the value of name which is 'alx' as xx[0].name, but how should I retrieve value of 'name' itself? By that, I mean how can I fetch the key at run time?

First of all, it's not xx[0].name, it's xx.name. Or, more correct, xx["name"]. — Felix
– Felix, Commented May 31, 2010 at 11:00
@Victor: because you can have keys with special characters, for example xx["some key"]. This is valid, yet you can't access it like xx.some key. That's why I prefer to always use the xx["name"] notation. — Felix
– Felix, Commented May 31, 2010 at 11:20
That makes it more flexible, not more correct. It is also less efficient since you have to create a string. — Quentin
– Quentin, Commented May 31, 2010 at 11:42

Vic · Accepted Answer · 2010-05-31 10:34:30Z

2

for (i in xx) {
    if (xx[i] == "alx") {
        // i is the key
    }
}

answered May 31, 2010 at 10:34

Vic

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1 Comment

Wondering Over a year ago

what if the other day value is not alx and something else.

Thariama · Accepted Answer · 2010-05-31 11:29:07Z

1

modified Code (from Victor) taking into account that you might want to look for any other possible string

var search_object = "string_to_look_for";
for (i in xx) {
    if (xx[i] == search_object) {
        // i is the key 
        alert(i+" is the key!!!"); // alert, to make clear which one
    }
}

edited May 31, 2010 at 11:29

answered May 31, 2010 at 10:39

Thariama

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3 Comments

Wondering Over a year ago

sorry, may b qs is not very clear, but is there a way to retrieve key without even considering the corresponding value

James Over a year ago

@Wondering, how will you identify what key you want then?

Sean Hogan Over a year ago

@Wondering, pay attention to the comment in that code. // i is the key

Sean Hogan · Accepted Answer · 2010-05-31 11:08:32Z

0

You are looking for associative arrays in Javascript. A quick google search suggests the following:

Read this page http://www.quirksmode.org/js/associative.html

and especially this section http://www.quirksmode.org/js/associative.html#link5

answered May 31, 2010 at 11:08

Sean Hogan

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