Setting an array of objects to sessionStorage

Question

Ok, so I have this JSON:

{"Status":"OK!","ListaPermessi":
[{"IdPermesso":10,"Nome":"WIND_PARAMS"},
 {"IdPermesso":11,"Nome":"ADMIN_SERVER"},
 {"IdPermesso":21,"Nome":"REC"},
 {"IdPermesso":22,"Nome":"REC_DIST"},
 {"IdPermesso":23,"Nome":"REC_DIST_CR"}
]}

My code is:

var parsedResult = JSON.parse(result); // where result is the above JSON
if (parsedResult.Status === "OK!") {
    // Set sessionStorage vars
    if (typeof(Storage) !== "undefined") {
        // localStorage & sessionStorage support!

        sessionStorage.setItem("ListaPermessi", parsedResult.ListaPermessi);
    }
    else {
        // Sorry! No web storage support :(
    }
}

But... this is not working properly! After the assignment, the sessionStorage seen from Firebug looks like this:

sessionStorage:

• ListaPermessi = "[object Object],[object Object],[object Object],[object Object],[object Object]"

What is the proper way to assign an array of objects to a sessionStorage variable from javascript?

Answer 1

You need to turn it back into a JSON string. You can do that with the JSON.stringify method:

sessionStorage.setItem("ListaPermessi", JSON.stringify(parsedResult.ListaPermessi));

The reason for this is that web storage can only store strings, and the default toString method of Object returns, as you've now seen, "[object Object]".

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Side note: typeof is an operator, not a function, so there's no need for the parentheses:

if (typeof Storage !== "undefined") { //...