Question

I hope my logic isn’t flawed but I’m reading the Definitive Guide to JavaScript and I don’t understand how this custom abs function works…

function abs(x) {
  if (x >= 0) {
    return x;
  } else {
    return -x;
  }
}

I recrafted it using a ternary operator in an attempt to understand it…

var res = (x >= 0) ? x : -x;
return res;

… but I still don’t get how it works.

Say I use -10 as x, how does it return +10? How does the sign reverse?

Answer 1

function abs(x) {
    if (x >= 0) {

        //If the number passed is greater than or equal to zero (positive)
        //return it back as is
        return x;

    } else {

        //If less than zero (negative)
        //return the negative of it (which makes it positive)
        // -(-10) === 10
        return -x;

    }
}