To convert a negative number to a positive one in JavaScript, use the abs() method in JavaScript. The method returns the absolute value of a number.
Example
You can try to run the following code to convert a negative number to positive −
<html>
<head>
<title>JavaScript Math abs() Method</title>
</head>
<body>
<script>
var value = Math.abs(-1);
document.write("First Test Value : " + value );
var value = Math.abs(null);
document.write("<br />Second Test Value : " + value );
var value = Math.abs(20);
document.write("<br />Third Test Value : " + value );
var value = Math.abs("string");
document.write("<br />Fourth Test Value : " + value );
</script>
</body>
</html>