You can use the conditional operator and the unary negation operator:

function absVal(integer) {
  return integer < 0 ? -integer : integer;
}

I think you can probably figure this one out just with a hint.

What happens to negative numbers when they are multiplied by -1?

Note that you can check if numbers are less than zero using if and then do something about less than zero numbers.

If you still get stuck after thinking on that for a few minutes shoot me a pm.

Edit: as long as you don't ask me to just write out all the code for you.

Use Math.abs():

Math.abs(-30) // 30

Edit: It seems that your syntax is of django templates but you ask about javasscript. if thats the case use django mathfilters

The Math.abs javascript function is designed exactly for getting the absolute value.

var x = -25;
x = Math.abs(x); // x would now be 25 
console.log(x);

Here are some test cases from the documentation:

Math.abs('-1');     // 1
Math.abs(-2);       // 2
Math.abs(null);     // 0
Math.abs("string"); // NaN
Math.abs();         // NaN

The absulute value in math function in JavaScript is Math.abs();

Math.abs(6-10) = 4;