Filtering an Array of Objects using Jquery $.grep without an Object Wrapper

Question

Filtering works fine for an object (data) wrapping around an array of objects:

var arr = {"data":
 [
  {"name":"Alan","height":"171","weight":"66"},
  {"name":"Ben","height":"182","weight":"90"},
  {"name":"Chris","height":"163","weight":"71"}
 ]
};

var new_arr = $.extend(true, arr);

new_arr.data = $.grep(new_arr.data, function(n, i){
  return n.weight > 70;
});

alert(new_arr.data.length); // answer is 2

However, filtering without the object wrapper doesn't.

var arr = [
  {"name":"Alan","height":"171","weight":"66"},
  {"name":"Ben","height":"182","weight":"90"},
  {"name":"Chris","height":"163","weight":"71"}
 ];

var new_arr = $.extend(true, arr);

new_arr = $.grep(new_arr, function(n, i){
  return n.weight > 70;
});

alert(new_arr.length); // answer is 1 instead of 2

I am not sure where is the problem. Can anyone point out. Thanks!

Dane O'Connor · Accepted Answer · 2011-12-15 14:27:31Z

10

You're using extend incorrectly. You can't extend the new_arr with an array. Extend will add methods/props to an object but what methods/props will it create when it runs into your array? This is why it works with the object wrapper: 1) extend expects an object and 2) 'data' is a property that can be added to new_arry.

Despite, in your second example, it doesn't look like you need to extend anything. Does this work?

new_arr = $.grep(arr, function(n, i){ // just use arr
  return n.weight > 70;
});

edited Dec 15, 2011 at 14:27

answered Dec 15, 2011 at 14:22

Dane O'Connor

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1 Comment

Question Overflow Over a year ago

I just found out the reason too :) I forgot why I used extend in the first place. It seems I don't need it now. Thanks a lot :)

David Lopes · Accepted Answer · 2017-09-29 10:54:55Z

1

You can use this to a object more deep,

var prodIds = [];

        $.grep(this.prodOrders, function (n, i) { 

            $.grep(n.ProductionOrderLines, function (n2, i2) { 
                if (n2.ItemNo == resource) {
                    prodIds.push(n2.DocumentAbsoluteEntry);
                }
            });
        });

answered Sep 29, 2017 at 10:54

David Lopes

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