Detailed code explanation for JavaScript implementation of Base64 encoding and decoding

This article shares with you a detailed code explanation of jJavaScript's implementation of Base64 encoding and decoding. The content is quite good. I hope it can help friends in need.

1. Encryption and decryption Method using

//1.加密 var str = '124中文内容'; 
var base = new Base64(); 
var result = base.encode(str); 
//document.write(result); //2.解密 var result2 = base.decode(result); 
document.write(result2);

2. Encryption and decryption algorithm encapsulation:

/** 
* 
* Base64 encode / decode 
* 
* @author haitao.tu 
* @date 2010-04-26 
* @email tuhaitao@foxmail.com 
* 
*/function Base64() { 

 // private property 
 _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; 

 // public method for encoding 
 this.encode = function (input) { 
  var output = ""; 
  var chr1, chr2, chr3, enc1, enc2, enc3, enc4; 
  var i = 0; 
  input = _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 + 
   _keyStr.charAt(enc1) + _keyStr.charAt(enc2) + 
   _keyStr.charAt(enc3) + _keyStr.charAt(enc4); 
  } 
  return output; 
 } 

 // public method for decoding 
 this.decode = function (input) { 
  var output = ""; 
  var chr1, chr2, chr3; 
  var enc1, enc2, enc3, enc4; 
  var i = 0; 
  input = input.replace(/[^A-Za-z0-9\+\/\=]/g, ""); 
  while (i < input.length) { 
   enc1 = _keyStr.indexOf(input.charAt(i++)); 
   enc2 = _keyStr.indexOf(input.charAt(i++)); 
   enc3 = _keyStr.indexOf(input.charAt(i++)); 
   enc4 = _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 = _utf8_decode(output); 
  return output; 
 } 

 // private method for UTF-8 encoding 
 _utf8_encode = function (string) { 
  string = string.replace(/\r\n/g,"\n"); 
  var utftext = ""; 
  for (var n = 0; n < string.length; n++) { 
   var 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) { 
  var string = ""; 
  var i = 0; 
  var 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; 
 } 
}

Just introduce the encapsulation code and use it.

Related recommendations:

C language base64 encoding and decoding

Using base64 encoding and decoding in java

Base64 encoding

The above is the detailed content of Detailed code explanation for JavaScript implementation of Base64 encoding and decoding. For more information, please follow other related articles on the PHP Chinese website!