javascript - Problems create multidimensional array in localstorage - Stack Overflow

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I'm trying to save some data in localstorage. My script looks like this:

    localStorage.clear(); //only for testing

    if(typeof localStorage.akten == "undefined") {
        localStorage.akten = new Array();
    }

    var nam = "alpha";


    localStorage.akten[nam] = {
        "beta": 12
    };

    localStorage["a_akte"] = nam;

But if I do console.log(localStorage); or console.log(localStorage.akten); akten is only an empty string? Why? With an normal object instead of localStorage it works well.

I'm trying to save some data in localstorage. My script looks like this:

    localStorage.clear(); //only for testing

    if(typeof localStorage.akten == "undefined") {
        localStorage.akten = new Array();
    }

    var nam = "alpha";


    localStorage.akten[nam] = {
        "beta": 12
    };

    localStorage["a_akte"] = nam;

But if I do console.log(localStorage); or console.log(localStorage.akten); akten is only an empty string? Why? With an normal object instead of localStorage it works well.

• javascript
• html
• multidimensional-array
• local-storage

Share Improve this question Follow asked Sep 5, 2013 at 14:09 idmeanidmean 14.9k99 gold badges6161 silver badges8989 bronze badges 1

• JavaScript Array accepts only numerical indices. When you convert your array to JSON, the serialization will not include your arbitrary named properties (e.g. alpha). You should use an Object instead. And you can use literals (e.g. {} for Object and [] for Array). – eyelidlessness Commented Sep 5, 2013 at 14:13

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2 Answers 2

Sorted by: Reset to default 5

Suprisingly the devil is in the details. localStorage only stores strings. Encode your objects as JSON before depositing them there using for example JSON.stringify() and JSON.parse().

This is because localStorage is not an Object; it's an interface. You can only assign a String to it, and the best way to do so is with localStorage.setItem. If you want to be setting more plex data, you'll need to encode it as JSON first.

function localStore(key, obj) {
    return window.localStorage.setItem(key, JSON.stringify(obj));
}

function localGet(key) {
    return JSON.parse(window.localStorage.getItem(key));
}

localStore('foo', {bar: 'baz'});
localGet('foo'); // Object {bar: "baz"}

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