JavaScript code example for processing base64 encoding

This article brings you code examples about JavaScript processing base64 encoding. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Due to project requirements, base64 encoding needs to be processed and recorded again to facilitate subsequent calls.

About base64:

The essence of base64 is to Every 8-bit ASCII code becomes another every 6-bit code, and another reference table is used for corresponding translation.

The following is the js of base64:

var Base64 = {
    // 转码表
    table : [
        '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', '+', '/'
    ],
    UTF16ToUTF8 : function(str) {
        var res = [], len = str.length;
        for (var i = 0; i  0x0000 && code = 0x0080 && code > 6) & 0x1F);
                // 10xxxxxx
                var byte2 = 0x80 | (code & 0x3F);
                res.push(
                    String.fromCharCode(byte1),
                    String.fromCharCode(byte2)
                );
            } else if (code >= 0x0800 && code > 12) & 0x0F);
                // 10xxxxxx
                var byte2 = 0x80 | ((code >> 6) & 0x3F);
                // 10xxxxxx
                var byte3 = 0x80 | (code & 0x3F);
                res.push(
                    String.fromCharCode(byte1),
                    String.fromCharCode(byte2),
                    String.fromCharCode(byte3)
                );
            } else if (code >= 0x00010000 && code = 0x00200000 && code = 0x04000000 && code > 7) & 0xFF) == 0x0) {
                // 单字节
                // 0xxxxxxx
                res.push(str.charAt(i));
            } else if (((code >> 5) & 0xFF) == 0x6) {
                // 双字节
                // 110xxxxx 10xxxxxx
                var code2 = str.charCodeAt(++i);
                var byte1 = (code & 0x1F) > 4) & 0xFF) == 0xE) {
                // 三字节
                // 1110xxxx 10xxxxxx 10xxxxxx
                var code2 = str.charCodeAt(++i);
                var code3 = str.charCodeAt(++i);
                var byte1 = (code > 2) & 0x0F);
                var byte2 = ((code2 & 0x03) > 3) & 0xFF) == 0x1E) {
                // 四字节
                // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
            } else if (((code >> 2) & 0xFF) == 0x3E) {
                // 五字节
                // 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
            } else /** if (((code >> 1) & 0xFF) == 0x7E)*/ {
                // 六字节
                // 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
            }
        }

        return res.join('');
    },
    encode : function(str) {
        if (!str) {
            return '';
        }
        var utf8    = this.UTF16ToUTF8(str); // 转成UTF8
        var i = 0; // 遍历索引
        var len = utf8.length;
        var res = [];
        while (i > 2]);
            // 需要补2个=
            if (i == len) {
                res.push(this.table[(c1 & 0x3) > 4) & 0x0F)]);
                res.push(this.table[(c2 & 0x0F) > 4) & 0x0F)]);
            res.push(this.table[((c2 & 0x0F) > 6)]);
            res.push(this.table[c3 & 0x3F]);
        }

        return res.join('');
    },
    decode : function(str) {
        if (!str) {
            return '';
        }

        var len = str.length;
        var i   = 0;
        var res = [];

        while (i > 4);
            res.push(String.fromCharCode(c1));

            if (code3 != -1) {
                c2 = ((code2 & 0xF) > 2);
                res.push(String.fromCharCode(c2));
            }
            if (code4 != -1) {
                c3 = ((code3 & 0x3) <h3 id="Use">Use:</h3><p>Introduce JS first:</p><pre class="brush:php;toolbar:false"><script></script>

Use the method directly:

Base64.decode(content);

About the base64 of the picture:

Set src directly to your base64 in the picture to achieve decoding and display.

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