JSFiddle - React, Tailwind, and code Playground

JavaScript

var tracker = 0;
var inverse = false;

function handleDirection(src) {
  if (src) {
    inverse ? tracker-- : tracker++;
  } else {
    inverse ? tracker-- : tracker++;
  }
}

console.log(tracker);
handleDirection(true);
console.log(tracker); // Expect tracker to equal 1
handleDirection(false);
console.log(tracker); // Expect tracker to equal 2
inverse = true;
handleDirection(true);
console.log(tracker); // Expect tracker to equal 1
handleDirection(false);
console.log(tracker); // Expect tracker to equal 0