Twine Wiki

Just as you can tag a passage stylesheet to have its contents treated as CSS style rules, you can use the script tag to include custom Javascript in your story. All passages with this tag are executed when the game first loads, which you can use as an opportunity to do two things:

• Define custom macros made in Javascript by other Twine users.
• Modify how the Twine engine will work. To do this properly requires careful inspection of the Twine engine.

The execution order of passages tagged script is based on the alphabetical order of the script passages' names.

Remember: script passages must only contain Javascript.

• More details about coding in Twine can be found under Why Use Code?
• Other common questions are handled in the FAQ.

You may wish to use jQuery in your scripts to manipulate the page's structure, use AJAX, or just make general coding easier. But, you may also want other people to be able to use your script without having to set the StorySettings jQuery value themselves. There is another way for a story to request jQuery: simply put the case-insensitive words “requires jQuery” in a comment or a string inside your code:

//requires jquery

You can also request the Modernizr library with the words “requires Modernizr”.

A reminder: you do not need to call $.noConflict() when you first invoke jQuery in Twine 1.4 or higher.

Two objects exist in the Twine engine that are designed for custom script writers: prerender and postrender. If you add Javascript function properties to these objects, those function properties will be run every time a passage is rendered.

A postrender function looks something like this:

postrender.hello = function(a) {
    ...
    a.className += "hello"; // An example of 'a'
    console.log(this.title); // An example of 'this'
    ...
};

When postrender.hello is called, this is the Passage object which is currently being rendered, and the first argument a is the <div class=“body content”> element into which the passage's code has been rendered. You can thus transform or modify the div's contents in interesting ways.

postrender functions are called just after the passage's code is rendered into the div. prerender functions are called just before then.

Passage objects have the following structure (plus some other less useful properties):

• title: the string name of the passage.
• tags: an array of strings representing the passage's tags.
• text: the raw code of the passage.
• processText(): the code of the passage with some substitutions made - the “nobr” tag, if present, removes line breaks, and imported image syntax has the image's base64 data inserted.

If you use a lot of scripts from many people, note that as of 1.4.1, naming collisions in the macros, postrender and prerender objects (such as, adding macros which have the same name) are not alerted to the author. Take care that each addition to these objects has a unique name.

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