js的base32、base64编码方法实现

前言

由于业务需要，项目中涉及各种格式的编码解码实现，base32、base64网上大部分的博客文章出处都一致，但是都有小问题。如不兼容汉字转码、base32未进行补“=”操作的此类问题。然后自己通过网上已有的方法进行了改造，并通过测试比对，请放心使用。

一、js封装的方法源码

代码如下：

const Base64 = {
            _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
            encode: function (e) {
                var t = "";
                var n, r, i, s, o, u, a;
                var f = 0;
                e = Base64._utf8_encode(e);
                while (f < e.length) {
                    n = e.charCodeAt(f++);
                    r = e.charCodeAt(f++);
                    i = e.charCodeAt(f++);
                    s = n >> 2;
                    o = (n & 3) << 4 | r >> 4;
                    u = (r & 15) << 2 | i >> 6;
                    a = i & 63;
                    if (isNaN(r)) {
                        u = a = 64
                    } else if (isNaN(i)) {
                        a = 64
                    }
                    t = t + this._keyStr.charAt(s) + this._keyStr.charAt(o) + this._keyStr.charAt(u) + this._keyStr.charAt(a)
                }
                return t
            },
            decode: function (e) {
                var t = "";
                var n, r, i;
                var s, o, u, a;
                var f = 0;
                e = e.replace(/[^A-Za-z0-9+/=]/g, "");
                while (f < e.length) {
                    s = this._keyStr.indexOf(e.charAt(f++));
                    o = this._keyStr.indexOf(e.charAt(f++));
                    u = this._keyStr.indexOf(e.charAt(f++));
                    a = this._keyStr.indexOf(e.charAt(f++));
                    n = s << 2 | o >> 4;
                    r = (o & 15) << 4 | u >> 2;
                    i = (u & 3) << 6 | a;
                    t = t + String.fromCharCode(n);
                    if (u != 64) {
                        t = t + String.fromCharCode(r)
                    }
                    if (a != 64) {
                        t = t + String.fromCharCode(i)
                    }
                }
                t = Base64._utf8_decode(t);
                return t
            },
            _utf8_encode: function (e) {
                e = e.replace(/rn/g, "n");
                var t = "";
                for (var n = 0; n < e.length; n++) {
                    var r = e.charCodeAt(n);
                    if (r < 128) {
                        t += String.fromCharCode(r)
                    } else if (r > 127 && r < 2048) {
                        t += String.fromCharCode(r >> 6 | 192);
                        t += String.fromCharCode(r & 63 | 128)
                    } else {
                        t += String.fromCharCode(r >> 12 | 224);
                        t += String.fromCharCode(r >> 6 & 63 | 128);
                        t += String.fromCharCode(r & 63 | 128)
                    }
                }
                return t
            },
            _utf8_decode: function (e) {
                var t = "";
                var n = 0;
                var r = c1 = c2 = 0;
                while (n < e.length) {
                    r = e.charCodeAt(n);
                    if (r < 128) {
                        t += String.fromCharCode(r);
                        n++
                    } else if (r > 191 && r < 224) {
                        c2 = e.charCodeAt(n + 1);
                        t += String.fromCharCode((r & 31) << 6 | c2 & 63);
                        n += 2
                    } else {
                        c2 = e.charCodeAt(n + 1);
                        c3 = e.charCodeAt(n + 2);
                        t += String.fromCharCode((r & 15) << 12 | (c2 & 63) << 6 | c3 & 63);
                        n += 3
                    }
                }
                return t
            }
        }

        //  字符串转base64位的编码格式方法
        function stringToBase64(srcString){
            if (!srcString) {
                return '';
            }
            return Base64.encode(srcString);
        }

        //  字符串转base32位的编码格式方法
        function stringToBase32(srcString) {
            if (!srcString) {
                return '';
            }

            let BASE32CHAR = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
            let i = 0;
            let index = 0;
            let digit = 0;
            let currByte;
            let nextByte;
            let retrunString = '';
            // 先进行utf8编码，否则中文的字符串转码有问题
            srcString = Base64._utf8_encode(srcString);

            for (let i = 0; i < srcString.length;) {
                currByte = (srcString.charCodeAt(i) >= 0) ? srcString.charCodeAt(i)
                    : (srcString.charCodeAt(i) + 256);

                if (index > 3) {
                    if ((i + 1) < srcString.length) {
                        nextByte = (srcString.charCodeAt(i + 1) >= 0)
                            ? srcString.charCodeAt(i + 1)
                            : (srcString.charCodeAt(i + 1) + 256);
                    } else {
                        nextByte = 0;
                    }

                    digit = currByte & (0xFF >> index);
                    index = (index + 5) % 8;
                    digit <<= index;
                    digit |= (nextByte >> (8 - index));
                    i++;
                } else {
                    digit = (currByte >> (8 - (index + 5))) & 0x1F;
                    index = (index + 5) % 8;

                    if (index == 0) {
                        i++;
                    }
                }

                retrunString = retrunString + BASE32CHAR.charAt(digit);
            }

            // 不满8位的需要进行补“=”号，这是base32转码的规范
            while((retrunString.length % 8) !== 0){
                retrunString += "=";
            }

            return retrunString;
        }

二：使用实例

stringToBase32("马到成功")
// 转换为："5GU2ZZMIWDTIREHFRKPQ===="

stringToBase64("马到成功")
// 转换为："6ams5Yiw5oiQ5Yqf"