在 JavaScript 中表达 UTF-16 Unicode 字符
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Expressing UTF-16 unicode characters in JavaScript
提问by gilly3
To express, for example, the character U+10400 in JavaScript, I use "\uD801\uDC00"or String.fromCharCode(0xD801) + String.fromCharCode(0xDC00). How do I figure that out for a given unicode character? I want the following:
例如，为了表达 JavaScript 中的字符 U+10400，我使用"\uD801\uDC00"或String.fromCharCode(0xD801) + String.fromCharCode(0xDC00)。我如何计算给定的 unicode 字符？我想要以下内容：
var char = getUnicodeCharacter(0x10400);
How do I find 0xD801and 0xDC00from 0x10400?
我如何找到0xD801和0xDC00来自0x10400？
回答by Arnaud Le Blanc
Based on the wikipedia articlegiven by Henning Makholm, the following function will return the correct character for a code point:
根据Henning Makholm 给出的维基百科文章，以下函数将返回代码点的正确字符：
function getUnicodeCharacter(cp) {
if (cp >= 0 && cp <= 0xD7FF || cp >= 0xE000 && cp <= 0xFFFF) {
return String.fromCharCode(cp);
} else if (cp >= 0x10000 && cp <= 0x10FFFF) {
// we substract 0x10000 from cp to get a 20-bits number
// in the range 0..0xFFFF
cp -= 0x10000;
// we add 0xD800 to the number formed by the first 10 bits
// to give the first byte
var first = ((0xffc00 & cp) >> 10) + 0xD800
// we add 0xDC00 to the number formed by the low 10 bits
// to give the second byte
var second = (0x3ff & cp) + 0xDC00;
return String.fromCharCode(first) + String.fromCharCode(second);
}
}
回答by Mathias Bynens
How do I find
0xD801and0xDC00from0x10400?
我如何找到
0xD801和0xDC00来自0x10400？
JavaScript uses UCS-2 internally.That's why String#charCodeAt()doesn't work the way you'd want it to.
JavaScript 在内部使用 UCS-2。这就是为什么String#charCodeAt()不能按照您希望的方式工作的原因。
If you want to get the code point of every Unicode character (including non-BMP characters) in a string, you could use Punycode.js's utility functions to convert between UCS-2 strings and UTF-16 code points:
如果您想获取字符串中每个 Unicode 字符（包括非 BMP 字符）的代码点，您可以使用Punycode.js的实用函数在 UCS-2 字符串和 UTF-16 代码点之间进行转换：
// String#charCodeAt() replacement that only considers full Unicode characters
punycode.ucs2.decode(''); // [119558]
punycode.ucs2.decode('abc'); // [97, 98, 99]
If you don't need to do it programmatically though, and you've already got the character, just use mothereff.in/js-escapes. It will tell you how to escape any character in JavaScript.
如果您不需要以编程方式执行此操作，并且您已经拥有该角色，则只需使用momeff.in/js-escapes。它会告诉你如何在 JavaScript 中转义任何字符。
