How to get the string length in bytes in nodejs? If I have a string, like this: äáöü then str.length will return with 4. But how to get that, how many bytes form the string?
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3A string does not have a length in bytes. This depends on the encoding used.usr– usr2012-03-25 22:38:10 +00:00Commented Mar 25, 2012 at 22:38
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6 Answers
Here is an example:
str = 'äáöü';
console.log(str + ": " + str.length + " characters, " +
Buffer.byteLength(str, 'utf8') + " bytes");
// äáöü: 4 characters, 8 bytes
function getBytes(string){
return Buffer.byteLength(string, 'utf8')
}
3 Comments
JohnnyHK
This is just a copy of the accepted answer, put into a function.
RReverser
Buffer.byteLength is already a such function, and example above at least shows it's usage. With the same luck you could do
var byteLength = Buffer.byteLength and it would also work just the same.
Intervalia
The simplest and best answer
Alternatively, you can use TextEncoder
new TextEncoder().encode(str).length
Related question
Assume it's slower though
Comments
This depends where the string is.
In JavaScript engines (at least, in most of them, including V8, used by Node.js and Chromium/Chrome), strings are encoded as UTF-16 internally. In UTF-16 encoding, every character is either 2 or 4 bytes long. Every character that's common in any major human language (and many that aren't) are encoded in 2 bytes (one code unit), while characters from rarer languages, emoji, and unusual symbols are often encoded in 4 bytes (two code units).
Moreover, the JavaScript string length property actually does not return the number of characters in the string, it returns the number of code units. For example, '😀'.length returns 2 even though the string contains only one character.
Finally, the strings are almost certainly (though I have not checked) null-terminated, so throw on an extra 2 bytes for that.
Putting it together, the length of a string residing in your Node.js script's memory is (str.length * 2) + 2 bytes.
On the other hand, when you send a string in an HTTP request, or write it to a file, it will typically be converted by default to UTF-8 before being transmitted to its destination. Characters in UTF-8 can be 1, 2, 3, or 4 bytes long (not counting the phenomenon of "over-long characters" and potential future expansion).
For this, I have nothing to add on top of the other answers to this question, which show how to calculate the length of a string in UTF-8.
Comments
console.log(Buffer.from('example..').length)
Comments
If you want to specific encoded, here is iconv example
var iconv = require('iconv-lite');
var buf =iconv.encode('äáöü', 'utf8');
console.log(buf.length);
// output: 8
