How to parse json in js?

Question

I need to parse a json object like {"key1":"val1","key2":"val2","key3":"val3"} in a loop.

Trying:

var inobj = '[{"key1":"val1","key2":"val2","key3":"val3"}]';
var obj = eval(inobj);
    for (var i = 0; i < 3; i++) {
        var key = i;
        var val = obj[key];
        alert (key+' = '+val);
    }

But i don't know hot to know obj.length.

Related: http://stackoverflow.com/questions/4935632/how-to-parse-json-in-javascript and http://stackoverflow.com/questions/11922383/i-have-a-nested-data-structure-json-how-can-access-a-specific-value — Felix Kling, Nov 06 '12 at 06:59

score 5 · Accepted Answer · answered Nov 06 '12 at 06:56

5

var obj = JSON.parse('{"key1":"val1","key2":"val2","key3":"val3"}');

Object.keys(obj).forEach(function (key) {
    alert(key + " = " + obj[key]);
});

answered Nov 06 '12 at 06:56

Domenic

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Or simply `for (var key in obj) {...}`. – Felix Kling Nov 06 '12 at 06:58
@FelixKling I prefer the `Object.keys(obj).forEach(function (key) { .. })` approach since it creates a new scope, avoiding the hoisting issues inherent in `for` loops. – Domenic Nov 06 '12 at 07:01
If a new scope is required then yes, it's a nice approach... otherwise, a simple `for` seems to have less overhead. – Felix Kling Nov 06 '12 at 07:03
1

Yeah, I mean, in this example a new scope is not necessarily required, but I can just imagine this user's next question being "why when I call `setTimeout` inside my `for` loop does it not work like I expect..." :) – Domenic Nov 06 '12 at 07:06

score 1 · Answer 2 · edited May 23 '17 at 12:18

1

You can count poperties:

Object.keys(obj).length

see stack question: How to efficiently count the number of keys/properties of an object in JavaScript?

edited May 23 '17 at 12:18

Community

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answered Nov 06 '12 at 06:57

karaxuna

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How to parse json in js?

2 Answers2