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This feature is well established and works across many devices and browser versions. Its been available across browsers since 2015 ..
charCodeAt() ( , 0x10000).
str.charCodeAt(index)
index, 0 ; , 0.
0 1114111 (0x10FFFF). 128 ASCII. JavaScript.
, charCodeAt() , 65536. , ( ) -, . , 65536 , charCodeAt(i), charCodeAt(i + 1) ( ). .
charCodeAt() NaN, .
: (, JavaScript 1.2) charCodeAt() ISO-Latin-1 . ISO-Latin-1 0 255. 127 ASCII.
charCodeAt()65, Unicode A.
"ABC".charCodeAt(0); // 65
charCodeAt() , for, , -.
function fixedCharCodeAt(str, idx) {
// , fixedCharCodeAt('\uD800\uDC00', 0); // 65536
// , fixedCharCodeAt('\uD800\uDC00', 1); // false
idx = idx || 0;
var code = str.charCodeAt(idx);
var hi, low;
// ( 0xDB7F,
//
// )
if (0xd800 <= code && code <= 0xdbff) {
hi = code;
low = str.charCodeAt(idx + 1);
if (isNaN(low)) {
throw " fixedCharCodeAt()";
}
return (hi - 0xd800) * 0x400 + (low - 0xdc00) + 0x10000;
}
if (0xdc00 <= code && code <= 0xdfff) {
//
// false, ,
//
//
return false;
// hi = str.charCodeAt(idx - 1);
// low = code;
// return ((hi - 0xD800) * 0x400) +
// (low - 0xDC00) + 0x10000;
}
return code;
}
charCodeAt() , function knownCharCodeAt(str, idx) {
str += "";
var code,
end = str.length;
var surrogatePairs = /[\uD800-\uDBFF][\uDC00-\uDFFF]/g;
while (surrogatePairs.exec(str) != null) {
var li = surrogatePairs.lastIndex;
if (li - 2 < idx) {
idx++;
} else {
break;
}
}
if (idx >= end || idx < 0) {
return NaN;
}
code = str.charCodeAt(idx);
var hi, low;
if (0xd800 <= code && code <= 0xdbff) {
hi = code;
low = str.charCodeAt(idx + 1);
// ,
return (hi - 0xd800) * 0x400 + (low - 0xdc00) + 0x10000;
}
return code;
}
| Specification |
|---|
| ECMAScript 2027 LanguageSpecification # sec-string.prototype.charcodeat |
String.fromCharCode()String.prototype.charAt()String.fromCodePoint()String.prototype.codePointAt()This page was last modified on 29 . 2026 . by MDN contributors.
StringString.prototype.anchor()at()String.prototype.big()String.prototype.blink()String.prototype.bold()String.prototype.charAt()String.prototype.charCodeAt()String.prototype.codePointAt()String.prototype.concat()String.prototype.endsWith()String.prototype.fixed()String.prototype.fontcolor()String.prototype.fontsize()String.prototype.includes()String.prototype.indexOf()isWellFormed()String.prototype.italics()String.prototype.lastIndexOf()String.prototype.link()String.prototype.localeCompare()String.prototype.match()String.prototype.matchAll()String.prototype.normalize()String.prototype.padEnd()String.prototype.padStart()String.prototype.repeat()String.prototype.replace()String.prototype.replaceAll()String.prototype.search()String.prototype.slice()String.prototype.small()String.prototype.split()String.prototype.startsWith()String.prototype.strike()String.prototype.sub()String.prototype.substr()String.prototype.substring()String.prototype.sup()String.prototype.toLocaleLowerCase()String.prototype.toLocaleUpperCase()String.prototype.toLowerCase()String.prototype.toString()String.prototype.toUpperCase()toWellFormed()String.prototype.trim()String.prototype.trimRight()String.prototype.trimLeft()String.prototype.valueOf()String.prototype[@@iterator]()Object/FunctionObject.prototype.__defineGetter__()Object.prototype.__defineSetter__()Object.prototype.__lookupGetter__()Object.prototype.__lookupSetter__()Object.prototype.hasOwnProperty()Object.prototype.isPrototypeOf()Object.prototype.propertyIsEnumerable()Object.prototype.toLocaleString()Object.prototype.toString()Object.prototype.valueOf()Your blueprint for a better internet.
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