Base64 是一组二进制到文本的编码方案,通过将二进制数据转换为基数 64 表示来表示 ASCII 字符串格式的二进制数据。
示例 1: 使用 btoa() 将字符串编码为 Base64
// program to encode a string to Base64 // defining the string const str = "Learning JavaScript"; // encoding the string const result = window.btoa(str); console.log(result); // decoding the string const result1 = window.atob(result); console.log(result1);
输出
TGVhcm5pbmcgSmF2YVNjcmlwdA== Learning JavaScript
在上面的例子中,
btoa()
方法用于将字符串转换为Base64。
atob()
方法用于将 Base64 转换为字符串。
示例 2: 使用 Base64 对象将字符串编码为 Base64
// program to encode a string to Base64 // create Base64 Object const Base64 = { // private property _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=", // public method for encoding encode : function (input) { let output = ""; let chr1, chr2, chr3, enc1, enc2, enc3, enc4; let i = 0; input = Base64._utf8_encode(input); while (i < input.length) { chr1 = input.charCodeAt(i++); chr2 = input.charCodeAt(i++); chr3 = input.charCodeAt(i++); enc1 = chr1 >> 2; enc2 = ((chr1 & 3) << 4) | (chr2 >> 4); enc3 = ((chr2 & 15) << 2) | (chr3 >> 6); enc4 = chr3 & 63; if (isNaN(chr2)) { enc3 = enc4 = 64; } else if (isNaN(chr3)) { enc4 = 64; } output = output + Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) + Base64._keyStr.charAt(enc3) + Base64._keyStr.charAt(enc4); } return output; }, // public method for decoding decode : function (input) { let output = ""; let chr1, chr2, chr3; let enc1, enc2, enc3, enc4; let i = 0; input = input.replace(/[^A-Za-z0-9\+\/\=]/g, ""); while (i < input.length) { enc1 = Base64._keyStr.indexOf(input.charAt(i++)); enc2 = Base64._keyStr.indexOf(input.charAt(i++)); enc3 = Base64._keyStr.indexOf(input.charAt(i++)); enc4 = Base64._keyStr.indexOf(input.charAt(i++)); chr1 = (enc1 << 2) | (enc2 >> 4); chr2 = ((enc2 & 15) << 4) | (enc3 >> 2); chr3 = ((enc3 & 3) << 6) | enc4; output = output + String.fromCharCode(chr1); if (enc3 != 64) { output = output + String.fromCharCode(chr2); } if (enc4 != 64) { output = output + String.fromCharCode(chr3); } } output = Base64._utf8_decode(output); return output; }, // private method for UTF-8 encoding _utf8_encode : function (string) { string = string.replace(/\r\n/g,"\n"); let utftext = ""; for (let n = 0; n < string.length; n++) { let c = string.charCodeAt(n); if (c < 128) { utftext += String.fromCharCode(c); } else if((c > 127) && (c < 2048)) { utftext += String.fromCharCode((c >> 6) | 192); utftext += String.fromCharCode((c & 63) | 128); } else { utftext += String.fromCharCode((c >> 12) | 224); utftext += String.fromCharCode(((c >> 6) & 63) | 128); utftext += String.fromCharCode((c & 63) | 128); } } return utftext; }, // private method for UTF-8 decoding _utf8_decode : function (utftext) { let string = ""; let i = 0; let c = c1 = c2 = 0; while ( i < utftext.length ) { c = utftext.charCodeAt(i); if (c < 128) { string += String.fromCharCode(c); i++; } else if((c > 191) && (c < 224)) { c2 = utftext.charCodeAt(i+1); string += String.fromCharCode(((c & 31) << 6) | (c2 & 63)); i += 2; } else { c2 = utftext.charCodeAt(i+1); c3 = utftext.charCodeAt(i+2); string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63)); i += 3; } } return string; } } // define the string const string = 'Learning JavaScript'; // encode the String const encodedString = Base64.encode(string); console.log(encodedString); // decode the String const decodedString = Base64.decode(encodedString); console.log(decodedString);
输出
TGVhcm5pbmcgSmF2YVNjcmlwdA== Learning JavaScript.
encode()
方法将字符串编码为 Base64、
decode()
方法将 Base64 解码为字符串。