Unexpected token u in JSON at position 0

Question

when I'm try to convert string to object I get error ``:

Unexpected token u in JSON at position 0

Service

setUser : function(aUser){ 
    //sauvegarder User       
    localStorage.setItem('User', JSON.stringify(aUser));
},

getUser : function(){
    //récuperer User      
    return JSON.parse(localStorage.getItem('User'));
}

Answer 1

The first thing to do is to look at what you're trying to parse. My guess is that you'll find it's "undefined", which is invalid JSON. You're getting undefined because you haven't (yet) saved anything to that key in local storage. undefined is then converted to the string "undefined" which JSON.parse can't parse.

I usually store and retrieve things in local storage like this:

Storing (just like yours):

localStorage.setItem("key", JSON.stringify(thing));

Retrieving (this is different):

thing = JSON.parse(localStorage.getItem("key") || "null");
if (!thing) {
    // There wasn't one, do whatever is appropriate
}

That way, I'm always parsing something valid.