localStorage array of objects handling

Question

Array of JSON objects are stored in HTML5 localStorage.
For now delimiter is ;
For accessing and modifying array of objects from localStorage, split(';') and join(';') operations used.

However ,delimiter approach looks unstable.
For instance ; could be met inside objects attribute and split(';') operation will be uncorrect.

It could be used ;; for delimiter,but i'm not certain it will be stable also.

Is there any robust way to handle localStorage presented as array of objects,as far localStorage saved as String?

EDIT

one of stoppers is that array of object couldn't be saved to localStorage as classical: "[{},{}]"
localStorage converts it automatially to String like "{},{}"

my current data within localStorage:

"{"name":"volvo","id":"033"};{"name":"saab","id":"034"}"

assumption
perhaps,i can add [ at the start and ] at the end,but it looks not gracefull

Cerbrus · Accepted Answer · 2012-12-04 12:00:09Z

44

Just convert the objects to JSON strings:

localStorage.setItem("savedData", JSON.stringify(objects));

And vice versa:

objects = JSON.parse(localStorage.getItem("savedData")));

Or you can add multiple objects in the same localStorage value:

localStorage.setItem("savedData", JSON.stringify([object1, object2 /*, etc*/]));
object1 = JSON.parse(localStorage.getItem("savedData"))[0];
object2 = JSON.parse(localStorage.getItem("savedData"))[1];

Here's the DOM storage specification.

You can also access savedData like this:

localStorage.savedData = "Hello world"
var foo = localStorage.savedData;

This can be used for both getting and setting the data, but it is considered less "safe" than getItem('name'); and setItem('name', 'value');

edited Dec 4, 2012 at 12:00

answered Dec 4, 2012 at 11:47

Cerbrus

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5 Comments

sergionni Over a year ago

hi, i've tested with just String in vacuum,it works OK,however problem is that array of JSON objects saved to localStorage as delimited by , curly brackets,e.g. "{obj1},{obj2}" and i expect "[{obj1},{obj2}]"

Cerbrus Over a year ago

Can you edit the actual object / data into your question? I'm not quite sure how the data you're trying to save looks, now. I'm confused because: JSON.stringify([{a:1}, {b:2}]); returns: "[{"a":1},{"b":2}]", like expected.

Cerbrus Over a year ago

I see. That's not a valid JSON string. Where are you getting this data from?

sergionni Over a year ago

i get it from backend using TidyJSONWriter,com.day.cq.commons.TidyJSONWriter

Cerbrus Over a year ago

Hm, I see. The easiest thing to do would be to make sure TidyJSONWriter uses , as delimiter instead of ; (If possible), then save that to your localStorage with added []: localStorage.savedData = '['+data+']' It's kinda ugly but at least it can be properly parsed, then.

RRikesh · Accepted Answer · 2012-12-04 11:48:45Z

0

Read variables:

var xyz = JSON.parse( localStorage.getItem( 'element' ) );

Store variables:

localStorage.setItem( 'element' , JSON.stringify(xyz));

where element is the name of the local storage variable and xyz the name of the js variable.

answered Dec 4, 2012 at 11:48

RRikesh

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