Get to Know State
We’d like to allow users to edit the word counter text. For this, we need some way to handle values that change over time: a classic book asserts that an object has state if its behavior is influenced by its history (Structure and Interpretation of Computer Programs [AS96]).
Let’s take a little detour to understand state. Open your browser’s JavaScript console and type the add function, which just adds its arguments together and returns the result:
| function add(x, y) { |
| return x + y; |
| } |
Then call the add method a few times:
| add(1,2); // returns 3 |
| add(5, 7); // returns 12 |
| add(1, 2); // returns 3 again |
| add(5, 7); // returns 12 again |
The return value of add depends only on its ...
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