The Window btoa() method is used for encoding a string in base-64 format.
The characters used by the Window btoa() method to encode the string are "A-Z", "a-z", "0-9", "+", "/" and "=" .
Syntax:
window.btoa(String)
Parameters Used:
- String: It is a mandatory parameter which specifies the string to be encoded.
Return Value: It returns a string that represents the encoded string of base-64.
Below program illustrates the Window btoa() Method:
Encoding a string in base-64 format.
<!DOCTYPE html>
<html>
<head>
<title>
Window btoa() Method in HTML
</title>
<style>
h1 {
color: green;
}
h2 {
font-family: Impact;
}
body {
text-align: center;
}
</style>
</head>
<body>
<h1>GeeksforGeeks</h1>
<h2>Window btoa() Method</h2>
<p>
For encoding a string in base-64 format,
double click the "Encode Message" button:
</p>
<button ondblclick="encode()">
Encode Message
</button>
<p id="myEncoding"></p>
<script>
function encode() {
var original = "GeeksforGeeks";
var encoded = window.btoa(original);
var output = "Encoded String : " + encoded;
document.getElementById("myEncoding").innerHTML =
"Original String: " + original + "<br>" + output;
}
</script>
</body>
</html>
Output:

After clicking the button:

Supported Browsers: The browser supported by Window btoa( ) Method are listed below:
- Google Chrome 4
- Edge 12
- Internet Explorer 10
- Firefox 1
- Opera 10.5
- Safari 3