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How to access JSON Array elements returned from an AJAX response

Answer 1

A:

Why can't you assign it to variable? Or I don't understand anything? :)

edited to work with json string

var ar = eval('[
{
lastInvAmt: 0
bwHrs: 0
nbwHrs: 0
unbilledAmt: 0
unbilledHrs: 0
dbID: 0
},{
lastInvAmt: 0
bwHrs: 0
nbwHrs: 0
unbilledAmt: 0
unbilledHrs: 0
dbID: 0
}]');

Why do you have single quote dbID: 0`. Is it spelling error?

Danil 2010-09-23 14:34:21

The OP probably gets above thingadongdong as a string in JSON, which he wants to be converted to a real object (or array, in this case).

Marcel Korpel 2010-09-23 14:40:34

then it is required to use eval of course. I will edit my code.

Danil 2010-09-23 14:48:54

No, it is not required and *could* even be dangerous (malicious code injection). Use a JSON parser instead.

Marcel Korpel 2010-09-23 14:54:07

yes that was a spelling error.

BinCode 2010-09-26 08:51:17

Answer 2

A:

That doesn't look like valid json data to me. It should look like this:

var json = { one: {
    lastInvAmt: 1,
    bwHrs: 2,
    nbwHrs: 3,
    unbilledAmt: 4,
    unbilledHrs: 5,
    dbID: 6
},
    two: {
        lastInvAmt: 11,
        bwHrs: 22,
        nbwHrs: 33,
        unbilledAmt: 44,
        unbilledHrs: 55,
        dbID: 66
    }
};

Then you access it like this:

arrJson = eval(json);
alert(arrJson['two']['lastInvAmt']);

etc...

Paul Spangle 2010-09-23 14:36:08

Your example contains a JavaScript object in literal notation, but you still use `eval` to do something?

Marcel Korpel 2010-09-23 14:37:36

Why would you use a string keyed object for numbering when there is a perfectly good array mechanism in JSON? You've actually made the original problem worse here.

Ollie Edwards 2010-09-23 15:10:35

Gosh - you're right. Didn't realise I'd been doing it so wrongly - thanks for the pointers.

Paul Spangle 2010-09-24 09:33:23

Answer 3

+1 A:

Apart from the fact that above thingadongdong^† isn't a valid JSON string (test this with jsonlint.com), you'll have to parse your returned string with something like JSON.parse or json-sans-eval.

After that, you can access your array like any other array, so you can count the number of elements using the length property.

Assuming your responseText contains a valid JSON string (with all strings encapsulated in double quotes and commas separating key/value pairs), like

[
    {
        "lastInvAmt": 0,
        "bwHrs": 0,
        "nbwHrs": 0,
        "unbilledAmt": 0,
        "unbilledHrs": 0,
        "dbID": 0 
    },
    {
        "lastInvAmt": 0,
        "bwHrs": 0,
        "nbwHrs": 0,
        "unbilledAmt": 0,
        "unbilledHrs": 0,
        "dbID": 0
    }
]

you can do something like

var myArray = JSON.parse(responseString);
var length = myArray.length;
alert(myArray[0].lastInvAmt);  // outputs '0'

^† _{See thingadongdong.com.}

Marcel Korpel 2010-09-23 14:50:49

Thanks! works like a charm

BinCode 2010-09-26 08:50:59

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How to access JSON Array elements returned from an AJAX response

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