Storing compressed json data in local storage

Question

I want to store JSON data in local storage. Sometimes data stored could be more than 5MB(max threshold allowed by browsers for each domain). Is there anyway i can compress or zip the data and store it in local storage ? How much latency it will add if compression and decompression for every JS function on large data ?

I am using this json data to display on webpage..... It is like a static data which is mostly same for entire session. we provide actions like search, filter etc on this json data...Whenever user enters a keyword, i search in this json data which is stored in local storage instead of making call to server

I am using this json data to display on webpage..... It is like a static data which is same for entire session. we provide actions like search, filter etc on this json data...Whenever user enters a keyword, i search in this json data which is stored in localstorage instead of making call to server — Rajeev
– Rajeev, Commented Dec 25, 2013 at 15:39
I highly doubt it. Local storage was not designed to hold large amounts of data. Why not store this data on the server's cache? — anar khalilov
– anar khalilov, Commented Dec 25, 2013 at 16:01
It seems rather exhaustive to unload everything you've got onto an unsuspecting user... 5MB? No amount of optimisation will compensate for those bandwidth implications - transfer just what you need when you need it in small chunks via ajax. — Emissary
– Emissary, Commented Dec 25, 2013 at 16:03
@Emissary - It is very less possibility of crossing size more than 5MB. Most of the times, i am serving the same response. For this scenario, why to send another request to server when i can serve from local storage? First time i want to get the data through ajax calls only. — Rajeev
– Rajeev, Commented Dec 25, 2013 at 16:14

Raunak Kathuria · Accepted Answer · 2020-01-31 04:08:04Z

32

As localStorage functionality seems to be limited to handle only string key/value pairs what you can do is to use lz-string library to stringify the json object and compress it before storing it in localStorage

Usage

// sample json object
var jsonobj = {'sample': 'This is supposed to be ling string', 'score': 'another long string which is going to be compressed'}

// compress string before storing in localStorage    
localStorage.setItem('mystring', LZString.compress(JSON.stringify(jsonobj)));

// decompress localStorage item stored
var string = LZString.decompress(localStorage.getItem('mystring'))

// parse it to JSON object
JSON.parse(string);

Check jsfiddle http://jsfiddle.net/raunakkathuria/7PQtC/1/ as i have copied the complete script so look for running code at end of fiddle

Use compressToUTF16 and decompressFromUTF16 if you are dealing with UTF characters but please note that the strings produced are therefore 6.66% bigger than those produced by compress. So use utf ones only when required.

edited Jan 31, 2020 at 4:08

answered Dec 25, 2013 at 16:06

Raunak Kathuria

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4 Comments

Rajeev Over a year ago

Do u suggest any ecryption algorithm for morphing before storing in local storage?

Raunak Kathuria Over a year ago

There is one code.google.com/p/crypto-js/#CryptoJS_3.1 but have not used any so cant suggest

mishmash Over a year ago

It says on the lz-string website that compress produces invalid UTF16 strings and will only work on webkit browsers. compressToUTF16 and compressFromUTF16 should be used for cross-browser compatibility.

Raunak Kathuria Over a year ago

Thanks @vanneto, updated the answer to reflect your comment.

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