What's the best way to query an array in javascript to get just the items from it I want?

Question

I have an array like this (with just over 3000 objects instead of the 3 here):

items = [{name:'charlie', age:'16'}, {name:'ben', age:'18'}, {name:'steve', age:'18'}] 

What's the best way to return an array with just the objects of people who are 18? So I want:

items = [{name:'ben', age:'18'}, {name:'steve', age:'18'}] 

The best I can think of is this (using jQuery):

newArray = [] $.each(items, function(index, item) {     if(item.age=='18') {         newArray.push(item)     } }) 

Considering that there's 3000 thousand objects, and also that I'll be doing that comparison up to fifty times in one go, that's a lot of looping. Is there a better way?

Answer 1

You can use pure javascript

var wanted = items.filter( function(item){return (item.age==18);} ); 

And if your browser does not support the 1.6 version of javascript you can find an implementation of the filter method at https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/filter

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Update

Speedwise there is a huge varying ^{(had an error in the test)} difference from a normal loop (depending on browser).. Have a look at this little test i made at http://jsperf.com/array-filter-vs-loop/3