Copy to Clipboard from input

gistfile1.txt

document.addEventListener('DOMContentLoaded', function() {
	var copybtn = document.getElementById('copybtn');
	var authcode = document.getElementById('authcode');
	copybtn.addEventListener('click', function() {
		// select the authorization code value
		authcode.setSelectionRange(0, authcode.value.length);
		
		try{
			// with text selected, execute the copy command
			var successful = document.execCommand('copy');  
			var msg = successful ? 'successful' : 'unsuccessful';
			if (msg == 'successful') copybtn.value = 'Copied!';
			console.log('Copy authorization code command was ' + msg);  
		} catch(err) {  
			console.log('Oops, unable to copy');  
		}
		
		// remove the selection
		window.getSelection().removeAllRanges();
	});
});