Manipulating JSON data sets

Question

So I have an array myarr[] of JSON objects in the form: { "a":"", "b":"" }

Are there efficient methods for getting an array of b:

[ myarr[0].b, myarr[1].b, myarr[2].b, ... ]

Or do I have to manually iterate through the myarr to build the array of b?

Answer 1

Check out the underscore.js library.

I'd suggest checking out the implementation for pluck .

What you'd want to do is effectively: _.pluck(myarr, 'b')

Answer 2

Why not have fun with prototypes and extend Array to obtain a handy and reusable function:

Array.prototype.pluck = function(key) {
    var i = this.length, 
        plucked = [];
    while(i --) {
        plucked[i] = this[i][key] || ""
    }

    return plucked;
}

With this one, you can do:

collection.pluck(keyName)

To get back your desired result. Check here for a working demo: http://jsfiddle.net/jYrNN/1/

Answer 3

var b_arr = $.map(myarr, function(val, i) { return val.b; });

FIDDLE

or wihtout jQuery

var b_arr = myarr.map(function(val) { return val.b })
                 .filter(function(n){return n || false});

Answer 4

jQuery does provide api to parse json

$.each(myarr, function(key,value)
  {
    alert(key);
    alert(value);
  });