40 lines
1.3 KiB
JavaScript
40 lines
1.3 KiB
JavaScript
const _String = String
|
|
|
|
export default _String.fromCodePoint || function stringFromCodePoint() {
|
|
var MAX_SIZE = 0x4000;
|
|
var codeUnits = [];
|
|
var highSurrogate;
|
|
var lowSurrogate;
|
|
var index = -1;
|
|
var length = arguments.length;
|
|
if (!length) {
|
|
return '';
|
|
}
|
|
var result = '';
|
|
while (++index < length) {
|
|
var codePoint = Number(arguments[index]);
|
|
if (
|
|
!isFinite(codePoint) || // `NaN`, `+Infinity`, or `-Infinity`
|
|
codePoint < 0 || // not a valid Unicode code point
|
|
codePoint > 0x10FFFF || // not a valid Unicode code point
|
|
Math.floor(codePoint) != codePoint // not an integer
|
|
) {
|
|
throw RangeError('Invalid code point: ' + codePoint);
|
|
}
|
|
if (codePoint <= 0xFFFF) { // BMP code point
|
|
codeUnits.push(codePoint);
|
|
} else { // Astral code point; split in surrogate halves
|
|
// http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
|
|
codePoint -= 0x10000;
|
|
highSurrogate = (codePoint >> 10) + 0xD800;
|
|
lowSurrogate = (codePoint % 0x400) + 0xDC00;
|
|
codeUnits.push(highSurrogate, lowSurrogate);
|
|
}
|
|
if (index + 1 === length || codeUnits.length > MAX_SIZE) {
|
|
result += String.fromCharCode.apply(null, codeUnits);
|
|
codeUnits.length = 0;
|
|
}
|
|
}
|
|
return result;
|
|
};
|