JS实现base64编码与解码

来源：互联网发布：uefitool for mac 编辑：程序博客网时间：2024/04/30 05:13
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);/** * base64编码 * @param {Object} str */function base64encode(str){    var out, i, len;    var c1, c2, c3;    len = str.length;    i = 0;    out = "";    while (i < len) {        c1 = str.charCodeAt(i++) & 0xff;        if (i == len) {            out += base64EncodeChars.charAt(c1 >> 2);            out += base64EncodeChars.charAt((c1 & 0x3) << 4);            out += "==";            break;        }        c2 = str.charCodeAt(i++);        if (i == len) {            out += base64EncodeChars.charAt(c1 >> 2);            out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));            out += base64EncodeChars.charAt((c2 & 0xF) << 2);            out += "=";            break;        }        c3 = str.charCodeAt(i++);        out += base64EncodeChars.charAt(c1 >> 2);        out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));        out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));        out += base64EncodeChars.charAt(c3 & 0x3F);    }    return out;}/** * base64解码 * @param {Object} str */function base64decode(str){    var c1, c2, c3, c4;    var i, len, out;    len = str.length;    i = 0;    out = "";    while (i < len) {        /* c1 */        do {            c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];        }        while (i < len && c1 == -1);        if (c1 == -1)             break;        /* c2 */        do {            c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];        }        while (i < len && c2 == -1);        if (c2 == -1)             break;        out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));        /* c3 */        do {            c3 = str.charCodeAt(i++) & 0xff;            if (c3 == 61)                 return out;            c3 = base64DecodeChars[c3];        }        while (i < len && c3 == -1);        if (c3 == -1)             break;        out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));        /* c4 */        do {            c4 = str.charCodeAt(i++) & 0xff;            if (c4 == 61)                 return out;            c4 = base64DecodeChars[c4];        }        while (i < len && c4 == -1);        if (c4 == -1)             break;        out += String.fromCharCode(((c3 & 0x03) << 6) | c4);    }    return out;}/** * utf16转utf8 * @param {Object} str */function utf16to8(str){    var out, i, len, c;    out = "";    len = str.length;    for (i = 0; i < len; i++) {        c = str.charCodeAt(i);        if ((c >= 0x0001) && (c <= 0x007F)) {            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;}/** * utf8转utf16 * @param {Object} str */function utf8to16(str){    var out, i, len, c;    var char2, char3;    out = "";    len = str.length;    i = 0;    while (i < len) {        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) << 6) | (char2 & 0x3F));                break;            case 14:                // 1110 xxxx10xx xxxx10xx xxxx                char2 = str.charCodeAt(i++);                char3 = str.charCodeAt(i++);                out += String.fromCharCode(((c & 0x0F) << 12) | ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));                break;        }    }    return out;}//demo//function doit(){//    var f = document.f;//    f.output.value = base64encode(utf16to8(f.source.value));//    f.decode.value = utf8to16(base64decode(f.output.value));//}
0 0