Question

In C#, we have a .Sum(Predicate) method that lets you use a lambda expression to do a summation over a collection of objects. For instance, if I had the following set of objects (using JSON for simplicity)

[
  {
    "Id": 1,
    "Sub": {
      "Size": 1
    }
  },
  {
    "Id": 2,
    "Sub": {
      "Size": 3
    }
  }
]

And I wanted to get the sum of the sizes, I could do Sum(n => n.Sub.Size)

Is there a way to do something like this in javascript? I am really new (and weak) at the language and am having trouble performing a similar function. I am using jQuery, so I am open to that opening anything too.

Answer 1

var result = arr.reduce(function(a, b) {
    return a + b.Sub.Size;
}, 0);

Demo: http://jsfiddle.net/sUCTK/

Documentation: MDN