find highest number in array javascript

function findHighestNumber(nums) {
	
	let inputs = nums.filter((val, i) => nums.indexOf(val) === i)
	let max = Math.max(...nums);
	let min = Math.min(...nums);
  
   return max + (-min);
}

console.log(difference([1, 7, 18, -1, -2, 9]));Math.max(5, 10);function findHigestNumber(nums) {
	
	let inputs = nums.filter((val, i) => nums.indexOf(val) === i)
	let max = inputs.length - 1;
	let min = 0;

	for(let i = 0; i < inputs.length; i++) {
      
      if(inputs[i] > max) max = inputs[i];
      if(inputs[i] < min) min = inputs[i];
	}
  
   return max + (-min);
}

console.log(difference([1, 7, 18, -1, -2, 9]));