localstorage: Get specific localstorage value of which contains many items

Question

In localstorage I have key 'results' with this values:

[{"id":"item-1","href":"google.com","icon":"google.com"},
{"id":"item-2","href":"youtube.com","icon":"youtube.com"},
{"id":"item-3","href":"google.com","icon":"google.com"},
{"id":"item-4","href":"google.com","icon":"google.com"},
{"id":"item-5","href":"youtube.com","icon":"youtube.com"},
{"id":"item-6","href":"asos.com","icon":"asos.com"},
{"id":"item-7","href":"google.com","icon":"google.com"},
{"id":"item-8","href":"mcdonalds.com","icon":"mcdonalds.com"}]

To get the last item I use this:

// this is how I parse the arrays
var result = JSON.parse(localStorage.getItem("result")); 


for(var i=0;i<result.length;i++) {
    var item = result[i];
    $('element').val(item.href);
}

How can I get the href for item-3 or for a specific ID?

Answer 1

jQuery has filter helper for that:

$(result).filter(function(){return this.id == "item-3";})[0]

Function for href of item with specific id would be:

function getItemHrefById(json, itemId){
    return json.filter(function(testItem){return testItem.id == itemId;})[0].href;
}

And sample usage is:

var href = getItemHrefById(result, "item-3");

You can see working example on http://jsfiddle.net/LXvLB/

UPDATE

If you cannot read item from local storage, maybe you forgot to call JSON.stringify when setting value:

localStorage["results"] = JSON.stringify([{"id":"item-1","href":"google.com","icon":"google.com"}, 
{"id":"item-2","href":"youtube.com","icon":"youtube.com"}, 
{"id":"item-3","href":"google.com","icon":"google.com"}, 
{"id":"item-4","href":"google.com","icon":"google.com"}, 
{"id":"item-5","href":"youtube.com","icon":"youtube.com"}, 
{"id":"item-6","href":"asos.com","icon":"asos.com"}, 
{"id":"item-7","href":"google.com","icon":"google.com"}, 
{"id":"item-8","href":"mcdonalds.com","icon":"mcdonalds.com"}])

You need to convert json to string to be properly serialized (and to use JSON.parse to get JSON back)

This is final example.

EDIT

As Useless Code pointed out, this metod is substantially slower than native filter function (and custom loop but I think that introducing few new lines of code to save 20-30ms is overkill unless performance is a issue), so I'm updating my example to not use jquery filter. +1 please for his answer for that.

Also, what is important to point out here, if this array would have hundreds instead of 8 bookmarks, for loop would probably be statistically about twice faster (as it does not have to iterate through rest of the array). But, in that case it would probably be a good idea to put for loop into function which returns first found item which satisfies condition, and with prototypejs it probably can even be hooked up to array.