Complete example of base64 encryption and decryption implemented by JS

Complete example of base64 encryption and decryption implemented by JS_javascript skills

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Release： 2016-05-16 15:03:18

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The example in this article describes the base64 encryption and decryption implemented by JS. Share it with everyone for your reference, the details are as follows:

Full code:

<HTML>
<HEAD>
<TITLE>Base64</TITLE>
<script language=javascript>
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var 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);
<HTML>
<HEAD>
<TITLE>Base64</TITLE>
<script language=JavaScript>
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var 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);
function base64encode(str) {
　　var out, i, len;
　　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;
　　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;
}
function doit() {
　　var f = document.f
　　f.output.value = base64encode(utf16to8(f.source.value))
　　f.decode.value = utf8to16(base64decode(f.output.value))
}
</script>
</HEAD>
<BODY>
<H1>Base64</H1>
<FORM NAME="f">
原码<BR>
<TEXTAREA NAME="source" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR>
Base64 encode<BR>
<TEXTAREA NAME="output" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR>
Base64 decode<BR>
<TEXTAREA NAME="decode" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR>
<INPUT TYPE=BUTTON VALUE="转换" ONCLICK="doit()">
</FORM>
</BODY>

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For information on base64 encryption and decryption, you can also refer to the online tools on this website :

BASE64 encoding and decoding tool

For more encryption and decryption content, please refer to:

MD5 online encryption tool

URL hexadecimal encryption tool

Thunder, Express, Tornado URL encryption/decryption tools

Online SHA1 encryption tool

For more JavaScript-related content, please check out the special topics on this site: "Summary of JavaScript encryption and decryption techniques", "Summary of JavaScript switching effects and techniques", "JavaScript search Summary of Algorithm Skills", "Summary of JavaScript Animation Special Effects and Skills", "Summary of JavaScript Errors and Debugging Skills", "Summary of JavaScript Data Structure and Algorithm Skills》, "Summary of JavaScript traversal algorithms and techniques" and "Summary of JavaScript mathematical operation usage"

I hope this article will be helpful to everyone in JavaScript programming.