JSON.parse is giving an "undefined" object

Question

I tried to parse this string :

[{"ZoneId": "1", "0": "1", "ZoneX": "29", "1": "29", "ZoneY": "27", "2":     "27", "ZoneWidth": "76", "3": "76", "ZoneHeight": "61", "4": "61", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"},
{"ZoneId": "2", "0": "2", "ZoneX": "382", "1": "382", "ZoneY": "226", "2": "226", "ZoneWidth": "-117", "3": "-117", "ZoneHeight": "98", "4": "98", "ZoneImage": "46", "5": "46", "ZonePointTo": "3", "6": "3"},
{"ZoneId": "3", "0": "3", "ZoneX": "108", "1": "108", "ZoneY": "74", "2": "74", "ZoneWidth": "363", "3": "363", "ZoneHeight": "83", "4": "83", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"}]

Using JSON.parse() on this string show me "undefined" in the console. According to this site, my json is valid. It comes from a json_encode given by a php function.

If it can help, the final goal is to loop through this json array. Thanks.

[EDIT]

I realized that my error was in fact a scope issue using literal functions. Yes, I'm a bit stupid sometimes. Thanks everybody for your help!

Make sure that all the `"` are properly escaped when you input it to the parse. — David says Reinstate Monica, Feb 26 '15 at 05:03
Where is the string? How are you getting the object? How are you parsing it? You lack details — epascarello, Feb 26 '15 at 05:05
JSFiddle showing that the above does in-fact work fine with `JSON.parse`. http://jsfiddle.net/infiniteloops/sqwyxoo5/ — Gary.S, Feb 26 '15 at 05:05
JSON.parse() parses a 'string' as JSON. If you need to parse it with JSON.parse, I think an easy way is to enclose it with single quotes, using double quotes will not work as the content contains unescaped double quotes. — limekin, Feb 26 '15 at 05:07

score 5 · Accepted Answer · answered Feb 26 '15 at 05:03

This is no String, its a valid JSON which you can use in JavaScript:

var jsonData = [{"ZoneId": "1", "0": "1", "ZoneX": "29", "1": "29", "ZoneY": "27", "2":     "27", "ZoneWidth": "76", "3": "76", "ZoneHeight": "61", "4": "61", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"},
{"ZoneId": "2", "0": "2", "ZoneX": "382", "1": "382", "ZoneY": "226", "2": "226", "ZoneWidth": "-117", "3": "-117", "ZoneHeight": "98", "4": "98", "ZoneImage": "46", "5": "46", "ZonePointTo": "3", "6": "3"},
{"ZoneId": "3", "0": "3", "ZoneX": "108", "1": "108", "ZoneY": "74", "2": "74", "ZoneWidth": "363", "3": "363", "ZoneHeight": "83", "4": "83", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"}];

for(index in jsonData) {
    alert(JSON.stringify(jsonData[index]));
}

score 1 · Answer 2 · answered Oct 03 '20 at 13:21

your string is not json object
but
it is an json array object (check out the square brackets).
so to get the value you must run it into "for" or "each" or ...
.each example below
pass the string to variable and then ;

var obj=[{"ZoneId": "1", "0": "1", "ZoneX": "29", "1": "29", "ZoneY": "27", "2":     "27", "ZoneWidth": "76", "3": "76", "ZoneHeight": "61", "4": "61", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"},
{"ZoneId": "2", "0": "2", "ZoneX": "382", "1": "382", "ZoneY": "226", "2": "226", "ZoneWidth": "-117", "3": "-117", "ZoneHeight": "98", "4": "98", "ZoneImage": "46", "5": "46", "ZonePointTo": "3", "6": "3"},
{"ZoneId": "3", "0": "3", "ZoneX": "108", "1": "108", "ZoneY": "74", "2": "74", "ZoneWidth": "363", "3": "363", "ZoneHeight": "83", "4": "83", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"}]

            jQuery.each(obj, function(key,value) {
                alert(value.ZoneId);
            });

score 0 · Answer 3 · answered Feb 26 '15 at 05:11

If your having a return like this

var json_string =  "[{"0":"1","1":"29","2":"27","3":"76","4":"61","5":"46","6":"2","ZoneId":"1","ZoneX":"29","ZoneY":"27","ZoneWidth":"76","ZoneHeight":"61","ZoneImage":"46","ZonePointTo":"2"},{"0":"2","1":"382","2":"226","3":"-117","4":"98","5":"46","6":"3","ZoneId":"2","ZoneX":"382","ZoneY":"226","ZoneWidth":"-117","ZoneHeight":"98","ZoneImage":"46","ZonePointTo":"3"},{"0":"3","1":"108","2":"74","3":"363","4":"83","5":"46","6":"2","ZoneId":"3","ZoneX":"108","ZoneY":"74","ZoneWidth":"363","ZoneHeight":"83","ZoneImage":"46","ZonePointTo":"2"}]"

then you can use the JSON.parse() function

and it will decode the stringify json data

and it will return you

 [{"ZoneId": "1", "0": "1", "ZoneX": "29", "1": "29", "ZoneY": "27", "2":     "27", "ZoneWidth": "76", "3": "76", "ZoneHeight": "61", "4": "61", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"},
{"ZoneId": "2", "0": "2", "ZoneX": "382", "1": "382", "ZoneY": "226", "2": "226", "ZoneWidth": "-117", "3": "-117", "ZoneHeight": "98", "4": "98", "ZoneImage": "46", "5": "46", "ZonePointTo": "3", "6": "3"},
{"ZoneId": "3", "0": "3", "ZoneX": "108", "1": "108", "ZoneY": "74", "2": "74", "ZoneWidth": "363", "3": "363", "ZoneHeight": "83", "4": "83", "ZoneImage": "46", "5": "46", "ZonePointTo": "2", "6": "2"}]

since the return is already a json object then no need to use JSON.parse();

JSON.parse is giving an "undefined" object

3 Answers3