>Hi,
>
>Say I have the following strings (serialized JSON) (Key and Value in the local storage (simplified):
>
>

>"PM_ABCD","long string is here"
>"PM_1233", "another long string here"
>"ABC", "Another long string"
>"PM_G134555","long string"
>

>
>Can I get all keys - into an object - (without getting the Value) that start with a string "PM_"?

As Rob says you will need to iterate localStorage:

String.prototype.startsWith = function(startText) {
        return this.slice(0, startText.length) == startText;
    };
    
    var pmKeys = new Array();
    for (var x = 1; x < localStorage.length; x++) {
        var s = localStorage.key(x);
        if (s.startsWith("PM_")) {
            pmKeys.push(s);
        }
    }

But it may be better to store all those items as an array of objects under one key.e.g:

var toStore = [
    { Key: "PM_ABCD", Value: "long string is here" },
    { Key: "PM_1233", Value: "another long string here" },
    { Key: "ABC", Value: "Another long string here" },
    { Key: "PM_G134555", Value: "long string" }
];
localStorage.setItem("MyList", JSON.stringify(toStore));

Then you can pull them back into an array which is easier to manipulate:

var myList = JSON.parse(localStorage.getItem("MyList"));
var pmKeys = new Array();
    myList.forEach(function(item) {
        if (item.Key.slice(0, 3) == "PM_") {
            pmKeys.push(item.Key);
        }
    });

I usually pull any stuff that I'm likely to need from localStorage into memory when the page loads.