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up vote 0 down vote favorite

I have a Javascript array of objects and I would like to find index of the array element (object) where particular object's field is matching my search criteria.

That is, array looks like

  [{id:1, saved:0, name: "name1"}, {id:26, saved:0, name: "name2"},
    {id:3, saved:0, name: "name3"}, {id:15, saved:0, name: "name4"}]

and I would like to locate index of the element where element's id field is equal to, say, 15. I am using angular and jquery.

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6 Answers 6

up vote 4 down vote accepted

You'd have to iterate, here's a very simple example

var index = null;

for (var i=0; i<array.length; i++) {
    if ( array[i].id == 15 ) {
        index = i;
        break;
    }
}

That gets you the index, if you just want to return the object you can do

var obj = array.filter(function(obj) {
    return obj.id == 15;
}).shift();
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1  
I'd also break; after the index = i, just for performance. –  Chris Dixon May 9 at 14:41
1  
@ChrisDixon - Sounds like a good idea. –  adeneo May 9 at 14:42
up vote 1 down vote

array.filter is JavaScript's more elegant method for achieving this:

var arrr = [{id:1, saved:0, name: "name1"}, {id:26, saved:0, name: "name2"},
{id:3, saved:0, name: "name3"}, {id:15, saved:0, name: "name4"}];

return arrr.filter( function( value ){ return value.id == 15; })[0];
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up vote 0 down vote

Try this:

$.each(json.yourrootjson, function(i, v) {
    if (v.id == "15") {
        alert(v.id);
        alert(v.name);
        alert(v.saved);
        return;
    }
});
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up vote 2 down vote

There are multiple ways to do this.

You could iterate through the array and do a search.

var search = 15;
for(var index=0; index<input.length; index++) {
   if(input[index].id == search) {
       //Do whatever you want to do with this index.
   }
}

Or you could create a lookup first

var lookup = {};
for(var index=0; index<input.length; index++) {
   var element = input[index];
   lookup[element.id] = element;
   lookup[element.id].index = index;
}

Now, in every subsequent look-ups of a search term, you could do the following

var search = 15;
if(lookup[search]) {
   var index = lookup[search].index;
}
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up vote 0 down vote

Here is a very basic way to do it. Of course, you won't want to use the variables key and match statically like I did, but I will have to know more about your code to help you with that as well.

var array = [{id:1, saved:0, name: "name1"}, {id:26, saved:0, name: "name2"},
             {id:3, saved:0, name: "name3"}, {id:15, saved:0, name: "name4"}]

var key = 'id';
var match = 15;

array.forEach(function(elem, i) {
    if (elem[key] === match) {
        alert(i);
    }
});
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up vote 0 down vote

There are a lot of sources out there but a while loop appears to be the fastest way to iterate an array. Alternatively, Array.map() is in my opinion the cleanest way but actually turns out to be fairly slow.

Benchmarks

Article on loops

var array = []; // your array
var len = array.length;

while (len-- ) {
  if ( array[i].id == 15 ) {
    console.log(array[i])
  }
}
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