Is there any way to convert a base64 string to javascript?
In PHP we can do this:
base64_encode('stack overlow'); //c3RhY2sgb3Zlcmxvdw==
How can I do this in javascript?
Is there any way to convert a string to base 64 in javascript?
8
asked by anonymous 16.10.2015 / 17:13
3 answers
11
The modern answer is yes, with the native function btoa() , available in modern browsers.
btoa means base for asci, and there is the opposite that is atob .
In this case it would be:
btoa('stack overlow'); // "c3RhY2sgb3Zlcmxvdw=="
In older browsers this is not so simple and in this case I suggest a more complex function, type this .
Even in modern browsers, there are characters that can break the btoa() native function, for example:
btoa('✓ à la mode'); // Uncaught DOMException: Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.
In these cases you need to escape / convert these characters. In MDN these functions are suggested:
function utf8_to_b64(str) {
return window.btoa(unescape(encodeURIComponent(str)));
}
function b64_to_utf8(str) {
return decodeURIComponent(escape(window.atob(str)));
}
More info here in MDN . In this article there is also a workaround for characters that escape() addresses. Since escape() has always been deprecated (since ECMAScript v3 but has never actually been removed) it may be a case of using an alternative). Here it is:
function b64EncodeUnicode(str) {
return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, function(match, p1) {
return String.fromCharCode('0x' + p1);
}));
}
b64EncodeUnicode('✓ à la mode'); // "4pyTIMOgIGxhIG1vZGU="
16.10.2015 / 17:21
6
The method btoa () can do the encode for you as well such as atob () does the decode. The return of
window.btoa('minha string')
is
bWluaGEgc3RyaW5n
and the return of
window.atob('bWluaGEgc3RyaW5n')
It is, as expected
My string
EDIT
As pointed out by Omni , both methods are not supported for versions prior to IE 10 (always it).
16.10.2015 / 17:17
3
As mentioned, atob and btoa do not work in versions prior to IE10.
You can do this for your own conversion function (removed from here ):
var Base64 = {
_keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
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 + this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) + this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
}
return output;
},
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 = this._keyStr.indexOf(input.charAt(i++));
enc2 = this._keyStr.indexOf(input.charAt(i++));
enc3 = this._keyStr.indexOf(input.charAt(i++));
enc4 = this._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;
},
_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;
},
_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;
}
}
$encoded = Base64.encode("pt.stackoverflow.com");
alert($encoded)
$decoded = Base64.decode($encoded)
alert($decoded)
16.10.2015 / 17:27