Coin Change Calculator

I need to write function that calculates the coins you would use to give a customer their change in a shop. The function takes one argument, which is the amount of change needed, in pence. The function should always return an object. for example 13p change should be returned like this:

changeCalculator(13);
// should return {‘10’:1,‘2’:1,‘1’:1}

I’m stuck (new to coding), can someone direct me on ways to go about writing the function?

function changeCalculator (num) {

  var res = {};

  if (num < 0) return -1;
  if (num === 0) return 0;
  
  for (var i = 0; i < num.length; i++) {
      
  }
  return res;
};

Thank you,

We can’t write the code for you, but we can help you brainstorm and debug. What ideas have you had so far?