JavaScript實現的base62 encode/decode,用於頁面上直接對作為參數傳遞的url本身的編碼和解碼。

/** **************** define static table ***************** */<br />var encTable = new Array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K',<br />'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y',<br />'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',<br />'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0',<br />'1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/');</p><p>var decTable = new Array(256);<br />// initial decTable<br />for (i = 0; i < encTable.length; i++) {<br />decTable[encTable[i]] = i;<br />}<br />/** **************** end static table ***************** */</p><p>function encode(str) {<br />value = "";<br />pos = 0, val = 0;<br />for ( var i = 0; i < str.length; i++) {<br />val = (val << 8) | (str.charCodeAt(i) & 0xFF);<br />pos += 8;<br />while (pos > 5) {<br />c = encTable[val >> (pos -= 6)];<br />value += c == 'i' ? "ia" : c == '+' ? "ib" : c == '/' ? "ic" : c;<br />val &= ((1 << pos) - 1);<br />}<br />}<br />if (pos > 0) {<br />value += encTable[val << (6 - pos)];<br />if (pos == 2) {<br />value += "==";<br />} else if (pos == 4) {<br />value += "=";<br />}<br />}<br />return value;<br />}</p><p>function decode(str) {</p><p>pos = 0, val = 0;<br />value = "";<br />for ( var i = 0; i < str.length; i++) {<br />c = str.charAt(i);<br />if (c == '=') {<br />break;<br />}<br />if (c == 'i') {<br />c = str.charAt(++i);<br />c = c == 'a' ? 'i' : c == 'b' ? '+' : c == 'c' ? '/' : str.charAt(--i);<br />}<br />val = (val << 6) | decTable[c];<br />pos += 6;<br />while (pos > 7) {<br />value += String.fromCharCode((val >> (pos -= 8)) & 0xFF);<br />val &= ((1 << pos) - 1);<br />}<br />}<br />return value;<br />}