Maximum String length
ljharb at gmail.com
Wed Jan 28 00:58:06 PST 2015
Typically, implementation-specific things aren't specified in the spec
(like Math precision, etc) - although usually when it's
implementation-specific, it's explicitly noted as such (
, https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.keys ,
Strings are only defined in ES6 as a "primitive value that is a finite
ordered sequence of zero or more 16-bit unsigned integer" (
) and are not noted as having any implementation-specific or
To me, "finite" here means `Number.MAX_VALUE` - ie, the highest number I
can get before I reach Infinity. An alternative reading is "any number
greater than zero that's not Infinity" - but at that point an
implementation conforms if it's max length is 1, which obviously would be
However, Chrome 40 and Opera 26-27 have a limit of `0xFFFFFF0` (`2**28 -
2**4`), Firefox 35 and IE 9-11 all have a limit of `0xFFFFFFF` (`2**28 -
1`), and Safari 8 has `0x7FFFFFFF` (`2**31 - 1`). There's many more
browsers I haven't tested of course but it'd be interesting to know how
wide these numbers deviate.
1) Should an engine's max string length be exposed, like
`Number.MAX_VALUE`, as `String.MAX_LENGTH`? This will help, for example, my
`String#repeat` polyfill throw an earlier `RangeError` rather than having
to try to build a string of that length.
2) Should the spec require a minimum maximum string length, or at least be
more specific in how it defines "finite"?
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