Does JS always use two bytes per character to store strings?

Question

I'm storing a very large ( >1MB ) bitmask in memory as a string and am curious about how JS stores strings internally. I have the feeling, based on the fact that

String.fromCharCode( 65535 ).charCodeAt( 0 ) === 65535

, that all strings are unicode, but I'm not certain. Basically I'm trying to find out if it would be more efficient, in terms of memory usage, to bitmask against 16-bit characters than 8-bit characters?

possible duplicate of How much RAM does each character in ECMAScript/JavaScript string consume? — jAndy
– jAndy, Commented Mar 6, 2013 at 23:13

Daniel Williams · Accepted Answer · 2013-03-06 23:13:42Z

1

Check this out:

https://developer.mozilla.org/en-US/docs/Mozilla_internal_string_guide#IDL_String_types

I believe it is very very browser dependent but the Mozilla documentation sheds some light on how they do it internally for JS strings.

The short answer is they use UTF-16

http://en.wikipedia.org/wiki/UTF-16

answered Mar 6, 2013 at 23:13

Daniel Williams

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Community · Accepted Answer · 2017-05-23 11:57:40Z

0

Check out this discussion.

JavaScript strings - UTF-16 vs UCS-2?

In short, just because some Javascript engines use a 16 bit encoding does NOT make it UTF16. Edge case surrogate pairs are handled MUCH differently between the two.

edited May 23, 2017 at 11:57

CommunityBot

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answered Mar 7, 2013 at 0:26

Jeremy J Starcher

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