Dropdown Menus and Cycling Links

Instead of allowing any kind of input at all from a player, you may want to contrain them to a specific set of choices. Chapbook has two mechanisms for this that look different to the player, but behave identically behind the scenes: menus and cycling links.

In order to do this, we need to introduce a new type of variable, an array. An array is similar to an object1 in that it's a container for other variables. However, where objects contain named variables, arrays are simply an ordered list of values. This array lists the colors of the rainbow:

['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']

Arrays are easy to spot: they simply put square brackets around a list of values separated by commas. An array can contain any type of value: ['red', 3, true] is a valid array. Arrays can also be empty, though in practice you'll rarely encounter this. The way to express an empty array is by writing [].

The {dropdown menu} insert displays a menu of choices to the player.

What meal do you enjoy most?

{dropdown menu for: 'meal', choices: ['Breakfast', 'Lunch', 'Dinner']}

As with text inputs, {dropdown menu} inserts save the selected value to a variable–in the example above, a variable named meal. If meal were previously set to a value in the menu, that value will be automatically preselected for the player. Otherwise, the menu shows the first option you list in the array of choices.

Unlike a text input, a dropdown menu does not block navigation to another passage, since it always has some value set.

The {cycling link} insert works exactly the same way as {dropdown menu}, only it shows a text link that the player selects to change. As the name implies, when the player reaches the last value in the choices array, the link starts over at the first element in the array.

I enjoy {cycling link for: 'meal', choices: ['Breakfast', 'Lunch', 'Dinner']} the most.

Optional Parts

Just like text inputs, dropdown menus and cycling links don't require that their value be saved to a variable. To do this, omit the for: part of the insert. For example, {cycling link, choices: ['Breakfast', 'Lunch', 'Dinner']}.

1. It is a peculiarity of JavaScript, the programming language of web browsers, that arrays are in fact implemented as objects, so in a sense arrays are objects. However, it's best to think of them at this stage as a distinct concept.

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