How to use a variable as an index to get a specific value out of a JSON array in Javascript?

Question

I simply want to pinpoint a specific value out of a JSON array.

Sample of JSON array:

{
    "00002": {
        "Job Number": "00002",
        "Company": "Corporate",
        "Supervisor": "Great Person",
        "Date Input": "2016-01-07"
    },

    "00003": {
        "Job Number": "00003",
        "Company": "SmallGuy",
        "Supervisor": "Awful Person",
        "Date Input": "2012-03-05"
    }
}

This works in Javascript:

alert(javascript_array["00002"].Company);

But I want use a dynamic variable to call a record, like this:

var my_variable = 00002;

//OR I've tried:

var my_variable = "'"+00002+"'";

alert(javascript_array[my_variable].Company); //DOES NOT WORK. UNDEFINED??

No matter what I do, I can't use a variable mid-array call.

Help please!

Sorry, I just made an edit. Ideally, "my_variable" would be 00002, 00003, up to 99999 really... — Graeme
– Graeme, Commented Mar 31, 2016 at 8:22
Just do: var my_variable = "00002", you are adding unneeded quotes ("'00002'"), which is why it can't find it. — Spencer Wieczorek
– Spencer Wieczorek, Commented Mar 31, 2016 at 8:23
Key variable must be a String, else, its toString() value will be used as key name. — s.d
– s.d, Commented Mar 31, 2016 at 8:35

Nina Scholz · Accepted Answer · 2016-03-31 08:32:10Z

2

Use the string as key.

var my_variable = '00002';

var object = { "00002": { "Job Number": "00002", "Company": "Corporate", "Supervisor": "Great Person", "Date Input": "2016-01-07" }, "00003": { "Job Number": "00003", "Company": "SmallGuy", "Supervisor": "Awful Person", "Date Input": "2012-03-05" } }
    my_variable = '00002';

document.write(object[my_variable].Company);

For getting all keys from the object, you can use Object.keys():

var object = { "00002": { "Job Number": "00002", "Company": "Corporate", "Supervisor": "Great Person", "Date Input": "2016-01-07" }, "00003": { "Job Number": "00003", "Company": "SmallGuy", "Supervisor": "Awful Person", "Date Input": "2012-03-05" } },
    keys = Object.keys(object);

keys.forEach(function (k) {
    document.write(object[k].Company + '<br>');
});

edited Mar 31, 2016 at 8:32

answered Mar 31, 2016 at 8:23

Nina Scholz

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Comments

fikkatra · Accepted Answer · 2016-03-31 08:24:25Z

1

Your key is a string, but your variable isn't, so there's no match. Just use this:

var my_variable = "00002";

answered Mar 31, 2016 at 8:24

fikkatra

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Comments

Spencer Wieczorek · Accepted Answer · 2016-03-31 08:49:30Z

0

To access key items for a JSON object you need to use strings, but if not it will attempt to convert the value into a string using .toString(). For your first case you are attempting to define a number:

var my_variable = 00002;

Although 00002 isn't a valid value for a number, as such it will contain the value 2, and converted to a string it's "2". In your JSON there is no such javascript_array["2"]. The second case has a similar problem:

"'"+00002+"'" => "'"+2+"'" => "'2'"

Also there is not such javascript_array["'2'"], along with this you are adding unneeded quotes '...'. In this case (as others pointed out) just define my_variable as a string with the value "00002".

var my_variable = "00002";

answered Mar 31, 2016 at 8:49

Spencer Wieczorek

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