JSON.stringify(localStorage) - filtering by key

Question

I use a small code snipped to save the localStorage of my application as a string:

var saveStr = JSON.stringify(localStorage);

It works great at a first glance, but it basically dump the entire localStorage object, which I don't want. I'd like to stringify the localStorage, but only the keys that contains a certain string.

For instance: var saveStr = JSON.stringify(filteredLS("example"));

filteredLS should return the localStorage data, but only the keys that contains the string that was passed as an argument.

Someone knows an easy snipped to achieve this?

Thanks!

Answer 1

Try this

function filteredLS(term) {
    var filteredObj = {};
    Object.keys(localStorage)

        .filter(function (key) {
            return key.indexOf(term) >= 0;
        })

        .map(function (key) {
            filteredObj[key] = localStorage.getItem(key);
        });

    return JSON.stringify(filteredObj);
}

Answer 2

You should use the methods localStorage.getItem and localStorage.setItem. With those, you can write your own get & set functions to easily use JSON objects:

function get(item) {
    return JSON.parse(localStorage.getItem(item))
}

function set(item, value) {
    return localStorage.setItem(item, JSON.stringify(value))
}

// use like this:
set('foo', { bar: 1 })
var result = get('foo')
// result: { bar: 1 }