how to create JavaScript object using a for loop?

Question

i have an object sample data:

[Object, Object, Object]
  0: Object
    test_id: "1"
    area: "high"
  1: Object
    test_id: "1"
    area: "saw"
  2: Object
    test_id: "2"
    area: "look"

i am trying to create a new object by grouping by test_id.

var obj = new Object();
$.each(data, function(k, v){
    obj[v.test_id] += {area: v.area};
});

this doesn't seem to work, it returns only one object line...

i am trying to get something like:

1: {
    {area: "high"}
    {area: "saw"}
}
2: {
    {area: "look""
}

any ideas? thanks

Man, you are doing some crazy stuff within those few code lines! :) — John Doe
– John Doe, Commented Jan 13, 2013 at 7:51

Benjamin Gruenbaum · Accepted Answer · 2013-01-13 07:57:22Z

1

After your edit I notice something, you're trying to create a javascript object with a property with no name, this is not the format. In JSON (javascript object notation) each property must have a value, what you are trying to store better fits an array.

Instead, push it into an array

    $.each(data, function(k, v){
    obj[v.test_id].area.push(v.area);
});

just remember to create obj[v.test_id] first and to set its area property to []. This results in:

1: {
    area: ["high","saw"]
}
3: {
    area: ["look"]
}

Also, if you're willing to consider using underscore it has very powerful (yet basic) collection methods, you might want to have a look at http://underscorejs.org/#groupBy

edited Jan 13, 2013 at 7:57

answered Jan 13, 2013 at 7:50

Benjamin Gruenbaum

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2 Comments

Patrioticcow Over a year ago

i edited. i meant those to be objects as well... but i guess i can always convert your array back into object

Benjamin Gruenbaum Over a year ago

Javascript objects are key value pairs, there is not much sense in code like {1: {{area: "high"},{area: "high"}}} , however, arrays make more sense and you can use {1: [{area: "high"},{area: "high"}}], this would be an object with a property called "1" that contains array of objects, each having an area property

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