JavaScript Tutorial/Math/log
Math.log()
The log() method of the Math object is used to calculate the natural logarithm (base E) of a number.
<html>
<body>
<script language="JavaScript">
<!--
function doMath(){
var inputNum=document.form1.input.value;
var result = Math.log(inputNum);
document.form1.answer.value = result;
}
-->
</script>
<form name=form1>
This example calculates the natural log of the number entered.
<br><br>
Enter First Number:
<input type="text" name="input" size=15>
<input type="button" value="Calculate" onClick="doMath()">
<br>
The log is:
<input type="text" name="answer" size=10>
</form>
</body>
</html>