How do I set a breakpoint in the global scope on Chrome Dev Tools?

Question

How do I set a breakpoint in the global scope on Chrome Dev Tools? I have my variables in the local function scope below. How would this look in the global scope? Thanks!

function calc() {
  var a = parseInt(document.querySelector('#value1').value);
  var b = parseInt(document.querySelector('#value2').value);
  var op = document.querySelector('#operator').value;
  var calculate;

  if (op == 'add') {
    calculate = a + b;
  } else if (op == 'min') {
    calculate = a - b;
  } else if (op == 'div') {
    calculate = a / b;
  } else if (op == 'mul') {
    calculate = a * b;
  }
  document.querySelector('#result').innerHTML = calculate;
}