Save Javascript file object to local storage

Question

I have a input type file where I save the file to a file object like so

var uploadControl = document.getElementById("fileUpload");
var files = uploadControl.files[0];

Then I would like to save that file to local storage to read into the FileReader object at a later time. Does anyone know if this is possible. I have tried several different options and every time I try and retrieve the object out of local storage, it is undefined.

Here are some things I have tried

var setObj = {"prop": "myProp", "file": files};
chrome.storage.sync.set({"myObj":setObj});

This doesn't throw errors, but when I try and retrieve the object, it is undefined

chrome.storage.sync.get("myObj", function(item) {
console.log("item name: " + item.myObj.file.name);
});

However I can access the other properties of the object

chrome.storage.sync.get("myObj", function(item) {
    console.log("item prop: " + item.myObj.prop);
    });

Am I doing something wrong when adding the object to local storage or am I accessing it incorrectly? Or is it just impossible to do this?

jgillich · Accepted Answer · 2013-03-12 18:29:26Z

3

localStorage can only contain string name/value pairs, which means you can not store an object directly.You can use stringify and parse for that.

answered Mar 12, 2013 at 18:29

jgillich

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3 Comments

abc123 Over a year ago

simply json serialize the object. :)

Jesse Kinsman Over a year ago

Guess I missed the key/value pair part of the local storage documentation. Thanks! That solves my problems.

Jesse Kinsman Over a year ago

Actually, that did solve my problem in terms of saving the object, but once I parse it, I am still unable to read it. I am guessing the file path information is removed when the object is converted to JSON. Has anyone successfully saved a file object and then read it later with the FileReader interface?

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