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<html><body><h1>The Window Object</h1><h2>The btoa() Method</h2><p>The btoa() method encodes a string in base-64.</p><p>The btoa() method is not supported in IE9 and earlier.</p><p id="demo"></p><script>let text = "Hello World!";let encoded = window.btoa(text);document.getElementById("demo").innerHTML = "Original: " + text + "<br>Encoded: " + encoded;</script></body></html>