number of arguments in nodejs code example

Example 1: javascript check if argument is passed

function func(arg1, arg2) {
  if (typeof arg2 === "undefined") {
    arg2 = "defaultValue";
  }
  
  //Rest of function
}

Example 2: javascript x number of parameters

function display_numbers(...numbers) {
	colors.forEach(function(x) {
  		console.log(x);
	});
}

// call it like:
display_numbers(1)
display_numbers(1, 2, 3, 4)
display_numbers(1, -1, 9, 0, 2)