程序传参的过程中对参数的处理常见的有 urlencode rawurlencode 等等这些函数，但在实际操作中作者发现这些函数处理起来总是会出些问题，最常见的urlencode在网页一连串的跳转过程中传参对&这个符号总是处理的有问题。经试验，作者发现还是使用base64_encode加密然后传参来的靠谱。
在php中对字符串进行base64_encode加密处理很容易，而且有相应的base64_decode函数进行解密，在js中却没有响应的处理方法，下面就和大家分享一个在js中实现php语言中的base64_encode base64_decode的方法。
function base64encode(str{
var out,i,len,base64EncodeChars="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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;
}
function base64decode(str{
var c1,c2,c3,c4,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;
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;
}
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;
}
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 xxxx 10xx xxxx 10xx xxxx
char2=str.charCodeAt(i++;
char3=str.charCodeAt(i++;
out+=String.fromCharCode(((c&0x0F<<12|((char2&0x3F<<6|((char3&0x3F<<0;
break;
}
}
return out;
}代码摘抄自网上，但做了些改进，网上流传的一些代码声明了两个比较大的全局变量，相对起来来说对性能有一些影响。
javascript实现base64_encode加密,解密的函数压缩下载
代码实例参照：base64编码加密,解密