atcheck/lsscanner/new_ubuntu/node_modules/utf8-byte-length/browser.js

48 lines
1.1 KiB
JavaScript

'use strict';
function isHighSurrogate(codePoint) {
return codePoint >= 0xd800 && codePoint <= 0xdbff;
}
function isLowSurrogate(codePoint) {
return codePoint >= 0xdc00 && codePoint <= 0xdfff;
}
// Truncate string by size in bytes
module.exports = function getByteLength(string) {
if (typeof string !== "string") {
throw new Error("Input must be string");
}
var charLength = string.length;
var byteLength = 0;
var codePoint = null;
var prevCodePoint = null;
for (var i = 0; i < charLength; i++) {
codePoint = string.charCodeAt(i);
// handle 4-byte non-BMP chars
// low surrogate
if (isLowSurrogate(codePoint)) {
// when parsing previous hi-surrogate, 3 is added to byteLength
if (prevCodePoint != null && isHighSurrogate(prevCodePoint)) {
byteLength += 1;
}
else {
byteLength += 3;
}
}
else if (codePoint <= 0x7f ) {
byteLength += 1;
}
else if (codePoint >= 0x80 && codePoint <= 0x7ff) {
byteLength += 2;
}
else if (codePoint >= 0x800 && codePoint <= 0xffff) {
byteLength += 3;
}
prevCodePoint = codePoint;
}
return byteLength;
};