Javascript convert localStorage getItem string to array

Question

I have an image gallery and I am storing the image names into localstorage using:

var user_selected_images = JSON.stringify(output);
localStorage.setItem('selectedFiles', user_selected_images);

When a image from the gallery is clicked,I want to check if the is image is present in the array.

var selFiles = localStorage.getItem('selectedFiles');
var selFiles = JSON.parse(selFiles);

When I try to assess the typeof variable

console.log(typeof selFiles)

I get an output as string. Currently my getItem output looks like this:

["STAR_SPORTS-00001.jpg","STAR_SPORTS-00002.jpg"]

I tried using jQuery.makeArray(selFiles) and various options that I could find in SO, but still my getItem remains as string and not as array.

That sounds unlikely. I get an array if I do var output = ["STAR_SPORTS-00001.jpg","STAR_SPORTS-00002.jpg"]; user_selected_images = JSON.stringify(output); console.log(user_selected_images); var selFiles = JSON.parse(user_selected_images); console.log(typeof selFiles,selFiles) Can you console.log something and perhaps there is an error somewhere — mplungjan
– mplungjan, Commented Feb 4, 2018 at 6:47
That can only happen if output is already a strifigied JSON. Can you try not to stringify and store it as it is. — 31piy
– 31piy, Commented Feb 4, 2018 at 6:48
Please update the question with the exact solution which you have. — Hassan Imam
– Hassan Imam, Commented Feb 4, 2018 at 6:49
Ithink output is already a JSON string... so this line is unnecessary JSON.stringify(output); ............. try localStorage.setItem('selectedFiles', output); — Pranav C Balan
– Pranav C Balan, Commented Feb 4, 2018 at 6:52

joshweir · Accepted Answer · 2018-02-04 06:50:36Z

1

Are you sure your output variable is not a string? If I initialize output like this:

var output = ["STAR_SPORTS-00001.jpg","STAR_SPORTS-00002.jpg"];

console.log(typeof selFiles) returns object as expected.

Then I initialize output like this:

var output = '["STAR_SPORTS-00001.jpg","STAR_SPORTS-00002.jpg"]';

console.log(typeof selFiles) returns a string like the problem you are having.

answered Feb 4, 2018 at 6:50

joshweir

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Racil Hilan · Accepted Answer · 2018-02-04 06:55:27Z

1

That's not possible, it must return object not string. See the test below. Also use Array.isArray() to test it:

var output = ["STAR_SPORTS-00001.jpg", "STAR_SPORTS-00002.jpg"]
var user_selected_images = JSON.stringify(output);
var selFiles = user_selected_images;
var selFiles = JSON.parse(selFiles);
console.log(typeof selFiles);
console.log(Array.isArray(selFiles));

Perhaps your output is already a JSON string, in which case you shouldn't use JSON.stringify() on it. Save it directly to localStorage:

localStorage.setItem('selectedFiles', output);

edited Feb 4, 2018 at 6:55

answered Feb 4, 2018 at 6:50

Racil Hilan

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