html5 window.localStorage.getItemItem get keys that start with

Question

How could I use

window.localStorage.getItem();

to specify items in localstarage that start with the string \'QQ\'. In my case the key

Answer 1

for ( var info in window.localStorage ){
 if ( info.substring( 0 , 2 ) === "QQ"){
  var data = window.localStorage.getItem( info ) );
  console.log(info);
 }

code not tested

Answer 2

Came across this and here is a solution in es6 :

let search = 'QQ';
let values = Object.keys(localStorage)
                   .filter( (key)=> key.startsWith(search) )
                   .map( (key)=> localStorage[key] );

Answer 3

You don't, get all the items and check them individually (code not tested):

var results = [];
for (i = 0; i < window.localStorage.length; i++) {
    key = window.localStorage.key(i);
    if (key.slice(0,2) === "QQ") {
        results.push(JSON.parse(window.localStorage.getItem(key)));
    }
}

If you want to do queries use something like IndexedDB.

Answer 4

I use this:

 var keyIndex = 0;
 var thisKey = window.localStorage.key(keyIndex);

 while(thisKey != '' && thisKey != undefined)
 {
    if (thisKey.substr(0, 2) == 'QQ')
    {
       // do whatever you need to do with thisKey
    }

    keyIndex+= 1;
    thisKey = window.localStorage.key(keyIndex);
 }

But robertc's solution is right too, it's a bit more simple that way. I actually changed my code to do a for loop too.