Javascript Reference - Window atob() Method

The atob() method decodes a base-64 encoded string.

Browser Support


`atob`	Yes	Yes	Yes	Yes	Yes

Syntax

window.atob(encodedStr)

Parameter Values

Parameter	Description
encodedStr	Required. The string which has been encoded by the btoa() method

Return Value

The decoded string

Example

The following code shows how to decode a base-64 encoded string.


<!DOCTYPE html>
<html>
<body>
<button onclick="myFunction()">test</button>
<!--   w  w  w . j a  va2s  . c  om-->
<p id="demo"></p>

<script>
function myFunction() {
    var str = "Hello World!";
    var enc = window.btoa(str);
    var dec = window.atob(enc);

    var res = "Encoded String: " + enc + "<br>" + "Decoded String: " + dec;
    document.getElementById("demo").innerHTML = res;
}
</script>

</body>
</html>

The code above is rendered as follows: