JavaScript/farenheit.html at master · Jeevan121/JavaScript · GitHub

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<html>
	<head>
		<script>

			//find celsius from fahrenheit javascript function
			//by tutorialsmade.com

			function findCelsius(){
				var fahrenheit = document.getElementById("Fahrenheit").value;
				var celsius;
				if(fahrenheit != ''){
					celsius = (fahrenheit - 32) * 5/9;
					document.getElementById("output").innerHTML = celsius;
				}else{
					document.getElementById("output").innerHTML = "Please enter a value!";
				}
			}

			//this is just to make sure if the user enter number or not, not actually needed for this program
			//this function will allow only numbers to be entered in the textbox
			function allowOnlyNumbers(evt) {
				evt = (evt) ? evt : window.event;
				var charCode = (evt.which) ? evt.which : evt.keyCode;
				if (charCode > 31 && (charCode < 48 || charCode > 57)) {
					return false;
				}
				return true;
			}

		</script>
	</head>
	<body>
		<h2>Enter Fahrenheit</h2>
		<input type="text" id="Fahrenheit" onkeypress="return allowOnlyNumbers()" />
		<strong>Fahrenheit</strong>

		<h4>Output: <span id="output"></span></h4>
	</body>
</html>