JS 實作BASE64_ENCODE和BASE64_DECODE(實例碼)_javascript技巧

複製程式碼 程式碼如下: /* utf.js - UTF-8 UTF-16 convertion * * Copyright (C) 1999 Masanao Izumo * Version: 1.0 * LastModified: Dec 25 1999 * This library is free. You can redistribute it and/or modify it. */ /* * Interfaces: * utf8 = utf16to8(utf16); * utf16 = utf16to8(utf8); */

function utf16to8(str) { var out, i, len, c;

out = ""; len = str.length; for(i = 0; i c = str.charCodeAt(i); if ((c >= 0x0001) && (c out += str.charAt(i); } else if (c > 0x07FF) { out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F)); out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } else { out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } } return out; }

function utf8to16(str) { var out, i, len, c; var char2, char3;

out = ""; len = str.length; i = 0; while(i c = str.charCodeAt(i++); switch(c >> 4) { case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: // 0xxxxxxx out += str.charAt(i-1); break; case 12: case 13: // 110x xxxx 10xx xxxx char2 = str.charCodeAt(i++); out += String.fromCharCode(((c & 0x1F) break; case 14: // 1110 xxxx 10xx xxxx 10xx xxxx char2 = str.charCodeAt(i++); char3 = str.charCodeAt(i++); out += String.fromCharCode(((c & 0x0F) ((char2 & 0x3F) ((char3 & 0x3F) break; } }

return out; }

/* * Interfaces: * b64 = base64encode(data); * data = base64decode(b64); */

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; var base64DecodeChars = new Array( -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);

function base64encode(str) { var out, i, len; var c1, c2, c3;

len = str.length; i = 0; out = ""; while(i c1 = str.charCodeAt(i++) & 0xff; if(i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt((c1 & 0x3) out += "=="; break; } c2 = str.charCodeAt(i++); if(i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3) > 4)); out += base64EncodeChars.charAt((c2 & 0xF) out += "="; break; } c3 = str.charCodeAt(i++); out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3) > 4)); out += base64EncodeChars.charAt(((c2 & 0xF) >6)); out += base64EncodeChars.charAt(c3 & 0x3F); } return out; }

function base64decode(str) { var c1, c2, c3, c4; var i, len, out;

len = str.length; i = 0; out = ""; while(i /* c1 */ do { c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff]; } while(i if(c1 == -1) break;

/* c2 */ do { } while(i if(c2 == -1) 與中斷使用;

out = String.fromCharCode((c1 > 4));

/* c3 */ do { if(c3 == 61) return出; return c3]; } while(i out = String.fromCharCode(((c2 & 0XF) > 2));

/* c4 */

do { if(c4 == 61)

return出; return c4]; } while(i out = String.fromCharCode(((c3 & 0x03 ) ) } return out; } //輸入base64編碼}