JavaScript实现的base62 encode/decode,用于页面上直接对作为参数传递的url本身的编码和解码。

/** **************** define static table ***************** */
var encTable = new Array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K',
		'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y',
		'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
		'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0',
		'1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/');

var decTable = new Array(256);
// initial decTable
for (i = 0; i < encTable.length; i++) {
	decTable[encTable[i]] = i;
}
/** **************** end static table ***************** */

function encode(str) {
	value = "";
	pos = 0, val = 0;
	for ( var i = 0; i < str.length; i++) {
		val = (val << 8) | (str.charCodeAt(i) & 0xFF);
		pos += 8;
		while (pos > 5) {
			c = encTable[val >> (pos -= 6)];
			value += c == 'i' ? "ia" : c == '+' ? "ib" : c == '/' ? "ic" : c;
			val &= ((1 << pos) - 1);
		}
	}
	if (pos > 0) {
		value += encTable[val << (6 - pos)];
		if (pos == 2) {
			value += "==";
		} else if (pos == 4) {
			value += "=";
		}
	}
	return value;
}

function decode(str) {

	pos = 0, val = 0;
	value = "";
	for ( var i = 0; i < str.length; i++) {
		c = str.charAt(i);
		if (c == '=') {
			break;
		}
		if (c == 'i') {
			c = str.charAt(++i);
			c = c == 'a' ? 'i' : c == 'b' ? '+' : c == 'c' ? '/' : str.charAt(--i);
		}
		val = (val << 6) | decTable[c];
		pos += 6;
		while (pos > 7) {
			value += String.fromCharCode((val >> (pos -= 8)) & 0xFF);
			val &= ((1 << pos) - 1);
		}
	}
	return value;
}