evaluate variable as part of JSON query [duplicate]

Question

I've got this:

var JSON = [
    {
        "id": 1,
        "name1": "Seymore Butts",
        "name2": "Jane Doe",
        "name3": "John Smith",
        "name4": "Mike Hawk"
    }];
for (i = 1; i < 5; i++) {
    var index = "name" + i;
    window.console.log(JSON[0].index);
}

and of course it's getting undefined because it's looking for

JSON[0].index

instead of

JSON[0].name1

Any way to force it to evaluate the index var instead of just reading "index"?

For future reference, you have an array of javascript objects, not JSON (which is always, by definition, a string) — jbabey
– jbabey, Commented Aug 2, 2013 at 17:43
possible duplicate of JavaScript object: access variable property by name as string, stackoverflow.com/questions/3153969/…, stackoverflow.com/questions/2241875/…, stackoverflow.com/questions/4694652/…, etc... — jbabey
– jbabey, Commented Aug 2, 2013 at 17:44

Kyle Fransham · Accepted Answer · 2013-08-02 17:44:24Z

4

Yup, just change your syntax to:

window.console.log(JSON[0][index]);

answered Aug 2, 2013 at 17:44

Kyle Fransham

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Comments

mishik · Accepted Answer · 2013-08-02 17:44:17Z

2

Use this:

for (i = 1; i < 5; i++) {
    var index = "name" + i;
    window.console.log(JSON[0][index]);
}

The difference between . and [] here is that object.sub_field will try to access field named sub_field, while object[sub_field] will try to access field named by "whatever is in variable sub_field".

answered Aug 2, 2013 at 17:44

mishik

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