Question

Both string and array objects contain, in addition to the length property, a number of properties that refer to function values.

var doh = "Doh";
console.log(typeof doh.toUpperCase);
// → function
console.log(doh.toUpperCase());
// → DOH

Every string has a toUpperCase property. When called, it will return a copy of the string, in which all letters have been converted to uppercase. There is also toLowerCase . You can guess what that does.

Interestingly, even though the call to toUpperCase does not pass any arguments, the function somehow has access to the string "Doh" , the value whose property we called. How this works is described in Chapter 6 .

Properties that contain functions are generally called methods of the value they belong to. As in, “ toUpperCase is a method of a string”.

This example demonstrates some methods that array objects have:

var mack = [];
mack.push("Mack");
mack.push("the", "Knife");
console.log(mack);
// → ["Mack", "the", "Knife"]
console.log(mack.join(" "));
// → Mack the Knife
console.log(mack.pop());
// → Knife
console.log(mack);
// → ["Mack", "the"]

The push method can be used to add values to the end of an array. The pop method does the opposite: it removes the value at the end of the array and returns it. An array of strings can be flattened to a single string with the join method. The argument given to join determines the text that is glued between the array’s elements.

This is a book about getting computers to do what you want them to do. Computers are about as common as screwdrivers today, but they contain a lot more hidden complexity and thus are harder to operate and understand. To many, they remain alien, slightly threatening things.