accessing-arguments

function myConcat(separator) {
  var result = ""; // initialize list
  var i;
  // iterate through arguments
  for (i = 1; i < arguments.length; i++) {
    result += arguments[i] + separator;
  }
  return result;
}

// returns "red, orange, blue, "
myConcat(", ", "red", "orange", "blue");

// returns "elephant; giraffe; lion; cheetah; "
myConcat("; ", "elephant", "giraffe", "lion", "cheetah");

// returns "sage. basil. oregano. pepper. parsley. "
myConcat(". ", "sage", "basil", "oregano", "pepper", "parsley");

// The rest parameter syntax allows us to represent
// an indefinite number of arguments as an array.
function multiply(multiplier, ...theArgs) {
  return theArgs.map(x => multiplier * x);
}

var arr = multiply(2, 1, 2, 3);
console.log(arr); // [2, 4, 6]