javascript - sessionStorage setItem returns true or false

Question

I'm trying to figure out what the setItem method from sessionStorage returns. As far as I could get, the following code returns undefined:

var set = sessionStorage.setItem('foo', 'bar');
console.log(set);

I need to know if the item was successfully set or if it failed. How can I accomplish this without knowing the return?

Answer 1

Take a look at the sessionStorage specification.

This line:

setter creator void setItem(DOMString key, DOMString value);

Tells us setItem doesn't return anything. (void is the return value, there)

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You can check if the item was set like this:

if (sessionStorage.getItem('myValue') == null){
    // myValue was not set
}else{
    // myValue was set
}