Punycode编码/解码的Javascript实现。

用法

const punycode = require('punycode');
console.log(punycode.encode('用法')); //nwwn1p
console.log(punycode.decode('nwwn1p')) //用法

console.log(punycode.toIDN('用法.中国')); //xn--nwwn1p.xn--fiqs8s
console.log(punycode.fromIDN('xn--nwwn1p.xn--fiqs8s')) //用法.中国

源代码

module.exports = (function() {
	var B = 1;
	var w = 26;
	var A = 36;
	var s = 128;
	var C = 72;
	var z = 700;
	var r = 38;
	var t = "-";
	var u = 2147483647;
	var v = {};
	var o = function(d, c) {
		return Math.floor(d / c)
	};
	var x = function(a, c, b) {
		a = o(a, b ? z : 2);
		a = a + o(a, c);
		var d = 0;
		while (a > o((A - B) * w, 2)) {
			a = o(a, A - B);
			d = d + A
		}
		return d + o((A - B + 1) * a, a + r)
	};
	var p = function(a) {
		return a < 128
	};
	var q = function(a) {
		if (a < 26) {
			return a + "a".charCodeAt(0)
		} else {
			if (a < 36) {
				return a - 26 + "0".charCodeAt(0)
			} else {
				return 0
			}
		}
	};
	var y = function(a) {
		if (a - "0".charCodeAt(0) < 10) {
			return a - "0".charCodeAt(0) + 26
		} else {
			if (a - "a".charCodeAt(0) < 26) {
				return a - "a".charCodeAt(0)
			} else {
				return 0
			}
		}
	};
	v.toIDN = function(c) {
		var b = c.split(".");
		var a = 0;
		var d = "";
		for (a = 0; a < b.length; a++) {
			if (/^[0-9a-zA-Z\\-]+$/igm.test(b[a])) {
				d += b[a] + "."
			} else {
				d += "xn--" + v.encode(b[a]) + "."
			}
		}
		if (d != "") {
			d = d.substr(0, d.length - 1)
		}
		return d
	};
	v.fromIDN = function(d) {
		var c = d.split(".");
		var a = 0;
		var e = "";
		for (a = 0; a < c.length; a++) {
			var b = c[a];
			if (b.toLowerCase().indexOf("xn--") == 0) {
				e += v.decode(b.substr(4)) + "."
			} else {
				e += b + "."
			}
		}
		if (e != "") {
			e = e.substr(0, e.length - 1)
		}
		return e
	};
	v.encode = function(d) {
		var e = s;
		var c = 0;
		var i = C;
		var b = "";
		var g = 0;
		d = d.split("");
		for (var k = 0; k < d.length; k++) {
			var h = d[k].charCodeAt(0);
			if (p(h)) {
				b += d[k];
				g++
			}
		}
		if (g > 0) {
			b += t
		}
		var j = g;
		while (j < d.length) {
			var n = u;
			for (var k = 0; k < d.length; k++) {
				var h = d[k].charCodeAt(0);
				if (h >= e && h < n) {
					n = h
				}
			}
			if (n - e > o(u - c, j + 1)) {
				return ""
			}
			c = c + (n - e) * (j + 1);
			e = n;
			for (var l = 0; l < d.length; l++) {
				var h = d[l].charCodeAt(0);
				if (h < e) {
					c++;
					if (0 == c) {
						return ""
					}
				}
				if (h == e) {
					var f = c;
					for (var m = A;; m += A) {
						var a;
						if (m <= i) {
							a = B
						} else {
							if (m >= i + w) {
								a = w
							} else {
								a = m - i
							}
						} if (f < a) {
							break
						}
						b += String.fromCharCode(q(a + (f - a) % (A - a)));
						f = o(f - a, A - a)
					}
					b += String.fromCharCode(q(f));
					i = x(c, j + 1, j == g);
					c = 0;
					j++
				}
			}
			c++;
			e++
		}
		return b
	};
	v.decode = function(e) {
		var f = s;
		var l = 0;
		var k = C;
		var d = "";
		var j = e.lastIndexOf(t);
		e = e.split("");
		if (j > 0) {
			for (var m = 0; m < j; m++) {
				var i = e[m].charCodeAt(0);
				if (!p(i)) {
					return ""
				}
				d += e[m]
			}
			j++
		} else {
			j = 0
		}
		while (j < e.length) {
			var h = l;
			var c = 1;
			for (var b = A;; b += A) {
				if (j == e.length) {
					return ""
				}
				var i = e[j++].charCodeAt(0);
				var g = y(i);
				if (g > o(u - l, c)) {
					return ""
				}
				l = l + g * c;
				var a;
				if (b <= k) {
					a = B
				} else {
					if (b >= k + w) {
						a = w
					} else {
						a = b - k
					}
				} if (g < a) {
					break
				}
				c = c * (A - a)
			}
			k = x(l - h, d.length + 1, h == 0);
			if (o(l, d.length + 1) > u - f) {
				return ""
			}
			f = f + o(l, d.length + 1);
			l = l % (d.length + 1);
			var n = String.fromCharCode(f);
			if (l == 0) {
				d = n + d
			} else {
				d = d.substr(0, l) + n + d.substr(l)
			}
			l++
		}
		return d
	};
	return v
})();