> Le 28 janv. 2015 à 09:58, Jordan Harband <ljh...@gmail.com> a écrit : > > 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-date.parse > <https://people.mozilla.org/~jorendorff/es6-draft.html#sec-date.parse> , > https://people.mozilla.org/~jorendorff/es6-draft.html#sec-math.hypot > <https://people.mozilla.org/~jorendorff/es6-draft.html#sec-math.hypot> , > https://people.mozilla.org/~jorendorff/es6-draft.html#sec-ecmascript-language-types-number-type > > <https://people.mozilla.org/~jorendorff/es6-draft.html#sec-ecmascript-language-types-number-type> > , https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.keys > <https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.keys> , etc) > > Strings are only defined in ES6 as a "primitive value that is a finite > ordered sequence of zero or more 16-bit unsigned integer" ( > https://people.mozilla.org/~jorendorff/es6-draft.html#sec-terms-and-definitions-string-value > > <https://people.mozilla.org/~jorendorff/es6-draft.html#sec-terms-and-definitions-string-value> > ) and are not noted as having any implementation-specific or > implementation-dependent qualities. > > 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 silly. >
To me, "finite" is just to be taken in the common mathematical sense of the term; in particular you could have theoretically a string of length 10^10000. But yes, it would be reasonable to restrict oneself to strings of length at most 2^52, so that `string.length` could always return an exact answer. —Claude > 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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