The map method is a convenient way to iterate through arrays.

gistfile1.txt

//The map method is a convenient way to iterate through arrays. Here's an example usage:

var timesFour = oldArray.map(function(val){
  return val * 4;
});
//The map method will iterate through every element of the array, creating a new array with values that have been modified by the callback function, and return it. Note that it does not modify the original array.

//In our example the callback only uses the value of the array element (the val argument) but your callback can also include arguments for the index and array being acted on.

//Use the map function to add 3 to every value in the variable oldArray, and save the results into variable newArray. oldArray should not change.