Speed/cost of localStorage

javascript html local-storage
Mike picture Mike · Nov 10, 2011 · Viewed 21.5k times · Source

How fast is looking up a value in localStorage with Javascript?

Does anyone have links to any performance tests that indicate whether or not it is worth caching the data in a JavaScript object? Or does the browser already cache values that are accessed from localStorage anyway?

I am particularly interested in Firefox and Chrome implementations of localStorage.

Answer

user166390 picture user166390 · Nov 10, 2011

For what it's worth, here is a jsperf test.

The benchmark usage of localStorage is significantly slower than access of a regular object properties in both FF7 and IE9. Of course, this is just a micro-benchmark, and does not necessarily reflect real-world usage or performance...

Sample pulled from my FF 7 run to show what "significantly slower" means, in ops/second:

            native     local-storage    notes
small set   374,397    13,657           10 distinct items
large set   2,256      68               100 distinct items
read-bias   10,266     342              1 write, 10 reads, 10 distinct items

Also, there are restrictions on what can be put in localStorage. YMMV.

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