From MDN. Using variable.apply() to allow the use of an array in place of standard delimited arguments without rewriting the original function.

function_with_array_or_delim_paramaters.js

// From MDN

function avg() {
  var sum = 0;
  for (var i = 0, j = arguments.length; i < j; i++) {
    sum += arguments[i];
  }
  return sum / arguments.length;
}

avg(2, 3, 4, 5); // 3.5

// Use the above function with an array without rewritting it
avg.apply(null, [2, 3, 4, 5]);