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

• John Doe: Man, you are doing some crazy stuff within those few code lines! :)
• Patrioticcow: @JohnDoe There is a always a way to complicate things :)

Answer 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

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