String length | js string length undefined
Thispropertyreturnsthenumberofcodeunitsinthestring.JavaScriptusesUTF-16[1]encoding,whereeachUnicodecharactermaybeencodedasoneortwocodeunits,soitspossibleforthevaluereturnedbylengthtonotmatchtheactualnumberofUnicodecharactersinthestring.ForcommonscriptslikeLatin,Cyrillic,wellknownCJKcharacters,etc.,thisshouldnotbeanissue,butifyouareworkingwithcertainscripts,suchasemojis,mathematicalsymbols[2],orobscureChinesecharacters,youmayneedtoaccountforthedifferencebetweencodeunitsandcharacters.Thelangua...
This property returns the number of code units in the string. JavaScript uses UTF-16[1] encoding, where each Unicode character may be encoded as one or two code units, so its possible for the value returned by length to not match the actual number of Unicode characters in the string. For common scripts like Latin, Cyrillic, wellknown CJK characters, etc., this should not be an issue, but if you are working with certain scripts, such as emojis, mathematical symbols[2], or obscure Chinese characters, you may need to account for the difference between code units and characters.
The language specification requires strings to have a maximum length of 253 - 1 elements, which is the upper limit for precise integers[3]. However, a string with this length needs 16384TiB of storage, which cannot fit in any reasonable devices memory, so implementations tend to lower the threshold, which allows the strings length to be conveniently stored in a 32-bit integer.
In V8 (used by Chrome an...