我有一个PHP脚本，可以将PNG图像编码为Base64字符串。
我想用JavaScript做同样的事情。我知道如何打开文件，但我不知道如何进行编码。我不习惯使用二进制数据。
当前回答
Sunny的代码很棒，只是因为引用了“this”而在Internet Explorer 7中崩溃了。通过将这些引用替换为"Base64"来修复:
var Base64 = {
// private property
_keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
// public method for encoding
encode : function (input) {
var output = "";
var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
var 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) {
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 = 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");
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;
}
}
其他回答
对于我的项目，我仍然需要支持IE7和工作大输入编码。
根据Joe Dyndale提出的代码和Marius在评论中提出的建议，可以通过使用数组而不是字符串构造结果来提高IE7的性能。
下面是encode的例子:
var encode = function (input) {
var output = [], chr1, chr2, chr3, enc1, enc2, enc3, enc4, 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.push(_keyStr.charAt(enc1));
output.push(_keyStr.charAt(enc2));
output.push(_keyStr.charAt(enc3));
output.push(_keyStr.charAt(enc4));
}
return output.join("");
};
这是一个缩小的填充窗口。Atob + window.btoa:
(function(){function t(t){this.message=t}var e="undefined"!=typeof exports?exports:this,r="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";t.prototype=Error(),t.prototype.name="InvalidCharacterError",e.btoa||(e.btoa=function(e){for(var o,n,a=0,i=r,c="";e.charAt(0|a)||(i="=",a%1);c+=i.charAt(63&o>>8-8*(a%1))){if(n=e.charCodeAt(a+=.75),n>255)throw new t("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");o=o<<8|n}return c}),e.atob||(e.atob=function(e){if(e=e.replace(/=+$/,""),1==e.length%4)throw new t("'atob' failed: The string to be decoded is not correctly encoded.");for(var o,n,a=0,i=0,c="";n=e.charAt(i++);~n&&(o=a%4?64*o+n:n,a++%4)?c+=String.fromCharCode(255&o>>(6&-2*a)):0)n=r.indexOf(n);return c})})();
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
// AMD. Register as an anonymous module.
define([], function() {factory(root);});
} else factory(root);
// node.js has always supported base64 conversions, while browsers that support
// web workers support base64 too, but you may never know.
})(typeof exports !== "undefined" ? exports : this, function(root) {
if (root.atob) {
// Some browsers' implementation of atob doesn't support whitespaces
// in the encoded string (notably, IE). This wraps the native atob
// in a function that strips the whitespaces.
// The original function can be retrieved in atob.original
try {
root.atob(" ");
} catch(e) {
root.atob = (function(atob) {
var func = function(string) {
return atob(String(string).replace(/[\t\n\f\r ]+/g, ""));
};
func.original = atob;
return func;
})(root.atob);
}
return;
}
// base64 character set, plus padding character (=)
var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
// Regular expression to check formal correctness of base64 encoded strings
b64re = /^(?:[A-Za-z\d+\/]{4})*?(?:[A-Za-z\d+\/]{2}(?:==)?|[A-Za-z\d+\/]{3}=?)?$/;
root.btoa = function(string) {
string = String(string);
var bitmap, a, b, c,
result = "", i = 0,
rest = string.length % 3; // To determine the final padding
for (; i < string.length;) {
if ((a = string.charCodeAt(i++)) > 255
|| (b = string.charCodeAt(i++)) > 255
|| (c = string.charCodeAt(i++)) > 255)
throw new TypeError("Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.");
bitmap = (a << 16) | (b << 8) | c;
result += b64.charAt(bitmap >> 18 & 63) + b64.charAt(bitmap >> 12 & 63)
+ b64.charAt(bitmap >> 6 & 63) + b64.charAt(bitmap & 63);
}
// If there's need of padding, replace the last 'A's with equal signs
return rest ? result.slice(0, rest - 3) + "===".substring(rest) : result;
};
root.atob = function(string) {
// atob can work with strings with whitespaces, even inside the encoded part,
// but only \t, \n, \f, \r and ' ', which can be stripped.
string = String(string).replace(/[\t\n\f\r ]+/g, "");
if (!b64re.test(string))
throw new TypeError("Failed to execute 'atob' on 'Window': The string to be decoded is not correctly encoded.");
// Adding the padding if missing, for semplicity
string += "==".slice(2 - (string.length & 3));
var bitmap, result = "", r1, r2, i = 0;
for (; i < string.length;) {
bitmap = b64.indexOf(string.charAt(i++)) << 18 | b64.indexOf(string.charAt(i++)) << 12
| (r1 = b64.indexOf(string.charAt(i++))) << 6 | (r2 = b64.indexOf(string.charAt(i++)));
result += r1 === 64 ? String.fromCharCode(bitmap >> 16 & 255)
: r2 === 64 ? String.fromCharCode(bitmap >> 16 & 255, bitmap >> 8 & 255)
: String.fromCharCode(bitmap >> 16 & 255, bitmap >> 8 & 255, bitmap & 255);
}
return result;
};
});
完整版https://github.com/MaxArt2501/base64-js/blob/master/base64.js
您可以在浏览器中使用btoa()/atob()，但需要一些改进，如https://base64tool.com/uncaught-domexception-btoa-on-window/和https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/btoa所述的UTF字符串支持!
Internet Explorer 10+
// Define the string
var string = 'Hello World!';
// Encode the String
var encodedString = btoa(string);
console.log(encodedString); // Outputs: "SGVsbG8gV29ybGQh"
// Decode the String
var decodedString = atob(encodedString);
console.log(decodedString); // Outputs: "Hello World!"
跨浏览器
// Create Base64 Object
var Base64={_keyStr:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",encode:function(e){var t="";var n,r,i,s,o,u,a;var f=0;e=Base64._utf8_encode(e);while(f<e.length){n=e.charCodeAt(f++);r=e.charCodeAt(f++);i=e.charCodeAt(f++);s=n>>2;o=(n&3)<<4|r>>4;u=(r&15)<<2|i>>6;a=i&63;if(isNaN(r)){u=a=64}else if(isNaN(i)){a=64}t=t+this._keyStr.charAt(s)+this._keyStr.charAt(o)+this._keyStr.charAt(u)+this._keyStr.charAt(a)}return t},decode:function(e){var t="";var n,r,i;var s,o,u,a;var f=0;e=e.replace(/[^A-Za-z0-9\+\/\=]/g,"");while(f<e.length){s=this._keyStr.indexOf(e.charAt(f++));o=this._keyStr.indexOf(e.charAt(f++));u=this._keyStr.indexOf(e.charAt(f++));a=this._keyStr.indexOf(e.charAt(f++));n=s<<2|o>>4;r=(o&15)<<4|u>>2;i=(u&3)<<6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r)}if(a!=64){t=t+String.fromCharCode(i)}}t=Base64._utf8_decode(t);return t},_utf8_encode:function(e){e=e.replace(/\r\n/g,"\n");var t="";for(var n=0;n<e.length;n++){var r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r)}else if(r>127&&r<2048){t+=String.fromCharCode(r>>6|192);t+=String.fromCharCode(r&63|128)}else{t+=String.fromCharCode(r>>12|224);t+=String.fromCharCode(r>>6&63|128);t+=String.fromCharCode(r&63|128)}}return t},_utf8_decode:function(e){var t="";var n=0;var r=c1=c2=0;while(n<e.length){r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r);n++}else if(r>191&&r<224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&31)<<6|c2&63);n+=2}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&15)<<12|(c2&63)<<6|c3&63);n+=3}}return t}}
// Define the string
var string = 'Hello World!';
// Encode the String
var encodedString = Base64.encode(string);
console.log(encodedString); // Outputs: "SGVsbG8gV29ybGQh"
// Decode the String
var decodedString = Base64.decode(encodedString);
console.log(decodedString); // Outputs: "Hello World!"
js小提琴
用node . js
下面是在Node.js中如何将普通文本编码为base64:
//Buffer() requires a number, array or string as the first parameter, and an optional encoding type as the second parameter.
// The default is "utf8". Possible encoding types are "ascii", "utf8", "ucs2", "base64", "binary", and "hex"
var b = Buffer.from('JavaScript');
// If we don't use toString(), JavaScript assumes we want to convert the object to utf8.
// We can make it convert to other formats by passing the encoding type to toString().
var s = b.toString('base64');
下面是解码base64编码字符串的方法:
var b = new Buffer('SmF2YVNjcmlwdA==', 'base64')
var s = b.toString();
. js和
使用dojox.encoding.base64对字节数组进行编码:
var str = dojox.encoding.base64.encode(myByteArray);
解码一个base64编码的字符串:
var bytes = dojox.encoding.base64.decode(str)
安装angular-base64
<script src="bower_components/angular-base64/angular-base64.js"></script>
angular
.module('myApp', ['base64'])
.controller('myController', [
'$base64', '$scope',
function($base64, $scope) {
$scope.encoded = $base64.encode('a string');
$scope.decoded = $base64.decode('YSBzdHJpbmc=');
}]);
我需要一个UTF-8字符串编码为Base64为我的一个项目。这里的大多数答案似乎在转换为UTF-8时不能正确处理UTF-16代理对，因此，为了完成，我将发布我的解决方案:
function strToUTF8Base64(str) {
function decodeSurrogatePair(hi, lo) {
var resultChar = 0x010000;
resultChar += lo - 0xDC00;
resultChar += (hi - 0xD800) << 10;
return resultChar;
}
var bytes = [0, 0, 0];
var byteIndex = 0;
var result = [];
function output(s) {
result.push(s);
}
function emitBase64() {
var digits =
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
'abcdefghijklmnopqrstuvwxyz' +
'0123456789+/';
function toDigit(value) {
return digits[value];
}
// --Byte 0-- --Byte 1-- --Byte 2--
// 1111 1122 2222 3333 3344 4444
var d1 = toDigit(bytes[0] >> 2);
var d2 = toDigit(
((bytes[0] & 0x03) << 4) |
(bytes[1] >> 4));
var d3 = toDigit(
((bytes[1] & 0x0F) << 2) |
(bytes[2] >> 6));
var d4 = toDigit(
bytes[2] & 0x3F);
if (byteIndex === 1) {
output(d1 + d2 + '==');
}
else if (byteIndex === 2) {
output(d1 + d2 + d3 + '=');
}
else {
output(d1 + d2 + d3 + d4);
}
}
function emit(chr) {
bytes[byteIndex++] = chr;
if (byteIndex == 3) {
emitBase64();
bytes[0] = 0;
bytes[1] = 0;
bytes[2] = 0;
byteIndex = 0;
}
}
function emitLast() {
if (byteIndex > 0) {
emitBase64();
}
}
// Converts the string to UTF8:
var i, chr;
var hi, lo;
for (i = 0; i < str.length; i++) {
chr = str.charCodeAt(i);
// Test and decode surrogate pairs in the string
if (chr >= 0xD800 && chr <= 0xDBFF) {
hi = chr;
lo = str.charCodeAt(i + 1);
if (lo >= 0xDC00 && lo <= 0xDFFF) {
chr = decodeSurrogatePair(hi, lo);
i++;
}
}
// Encode the character as UTF-8.
if (chr < 0x80) {
emit(chr);
}
else if (chr < 0x0800) {
emit((chr >> 6) | 0xC0);
emit(((chr >> 0) & 0x3F) | 0x80);
}
else if (chr < 0x10000) {
emit((chr >> 12) | 0xE0);
emit(((chr >> 6) & 0x3F) | 0x80);
emit(((chr >> 0) & 0x3F) | 0x80);
}
else if (chr < 0x110000) {
emit((chr >> 18) | 0xF0);
emit(((chr >> 12) & 0x3F) | 0x80);
emit(((chr >> 6) & 0x3F) | 0x80);
emit(((chr >> 0) & 0x3F) | 0x80);
}
}
emitLast();
return result.join('');
}
注意，代码没有经过彻底的测试。我测试了一些输入，包括strToUTF8Base64('衠衢蠩蠨')，并将其与在线编码工具(https://www.base64encode.org/)的输出进行了比较。
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