Localstorage: Change value for a specific array using Stringify

Question

I don't know if the question is very accurate but I'm trying to change a value from a localstorage array.

This is what my localstorage looks like:

[{"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"}]

The key is 'result'.

How can I setItem for id:item-6, href:. So for example. The item-6, href is asos.com. How can I set change that to stackoverflow.com ?

I assume It will be something like this:

localStorage.setItem("result", JSON.stringify( ??? ));

EDIT:

I already achieved to retrieve the data from the localstorage: Here is the working fiddle: http://jsfiddle.net/kZN4y/. Using the same coding, I want to update the value mentioned in the update click. Is that possible?

Thanks

Answer 1

Personnally, I don't hesitate to create functions that handle the full object, in your case something like:

var blob = [{"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"}];

// define helper functions
Storage.prototype.setBlob = function (blob)
{
    for (i in blob) {
        // example of storageObjet: {'item-3': {'href': 'google.com', 'icon': 'google.png'}}
        var struct={};
        for (key in blob[i]) {
            if (key != 'id') {
                struct[key] = blob[i][key];
            }
        };
        this.setObject(blob[i].id, struct);
    }
}


Storage.prototype.setObject = function(key, obj) {
    this.setItem( key, JSON.stringify(obj) );    
};

Storage.prototype.getObject = function(key) {
    return JSON.parse(this.getItem(key));
};

// do stuff
sessionStorage.clear();
sessionStorage.setBlob(blob);

var key = 'item-6';
var item = sessionStorage.getObject(key);
item.href = 'stackoverflow.com';
sessionStorage.setObject(key, item);

for (key in sessionStorage) {
    if (typeof(sessionStorage[key]) == 'string') {
        var item2 = sessionStorage.getObject(key);
        $('#stuff').append( $('<div>').html(item2.href) );
    }
}

check this jsfiddle

NB: in this example I use sessionStorage instead of localStorage, but the interface is the same, both use Storage prototype.

As you see, I change the structure of each item to something like this: {'item-3': {'href': 'google.com', 'icon': 'google.png'}}. I do this because it reflects javascript, localStorage, and overall the concept of key/value way better, and eases the usage a lot.

in this example you there is:

var item = sessionStorage.getObject(key);
item.href = 'stackoverflow.com';
sessionStorage.setObject(key, item);

this looks a very practical way to handle localStorage to me.

Moreover, the "setBlob" function can handle a random and variable numbers of elements per item. This allows you to have one item having 5 attributes if you want, while all others have 2. It works with your "flat" structure as long as there is one element called with the key "id".

EDIT: debugged, and switched to a more classical setValue(key, item);