snipsnapper snipsnapper - 3 months ago 8
HTML Question

localStorage how to save a checkbox

I want to save a checkbox with localstorage. So that when i have checked the box and I close the browser and i re-open it, it will still be checked. right now if i click on the checkbox and i press the save button it doesn't save the checkbox.

how can i achieve this?

this is my code:

<script>
function save(){
var checkbox = document.getElementById('checkbox1zaal1');
if(document.getElementById('checkbox1zaal1').checked) {
localStorage.setItem('checkbox1zaal1', true);
}
}

function load(){
var checked = localStorage.getItem('checkbox1zaal1');
if (checked == true) {
document.getElementById("checkbox1zaal1").setAttribute('checked','checked');
}
}
function wis(){
location.reload();
localStorage.clear()

}
</script>

<body onload="load()">
<input type="button" id="ReserveerButton1" value="save" onclick="save()"/>
<input type="button" id="Wisbutton1" value="delete" onclick="wis()"/>
<input type="checkbox" id="checkbox1zaal1">1e film van de dag</input>
</body>


thanks for any advice!

Answer

1). Because boolean true is not equal to string "true". So comparison checked == true is always false, and checkbox never gets checked.

Instead try this:

var checked = JSON.parse(localStorage.getItem('checkbox1zaal1'));
if (checked == true) {
    document.getElementById("checkbox1zaal1").checked = true;
}

And remember whatever you store in localStorage is always a string, and only a string. That's why when you save something more complex then primitive value (for example some object) make sure to use JSON.stringify on it first.

When you retrieve the value from localStorage you should convert it back to it's corresponding javascript type.

In general load function can also be improved:

function load(){    
    var checked = JSON.parse(localStorage.getItem('checkbox1zaal1'));
    document.getElementById("checkbox1zaal1").checked = checked;
}

2). Another problem will come up once you try to uncheck checkbox. You are not handling it currently, so change save function to this one:

function save(){
    var checkbox = document.getElementById('checkbox1zaal1');
    localStorage.setItem('checkbox1zaal1', checkbox.checked);
}

Demo: http://jsfiddle.net/Lwxoeyyp/1/