CodeMirror for Foundry VTT

This package includes the CodeMirror editor library. A lightweight editor that can be used as a drop-in replacement for a textarea. The editor can be configured with text highlighting for various languages.

This module also provides a small number of user configurable settings you can use when creating an editor instance to allow a degree of customization.

Integration

Using the CM library as a dependency is very simple, this module already includes the following language modes:

javascript, css, xml, html, handlebars, markdown, toml, vue

Simply declare this module as a dependency by including the following in your manifest:

"dependencies": [
    {
        "name": "_CodeMirror",
        "type": "module",
        "manifest": "https://raw.githubusercontent.com/League-of-Foundry-Developers/codemirror-lib/master/module.json"	
    }
]

You can now create an instance of CM in any way outlined in the CM documnetation. The simplest method is to "upgrade" a textarea into a CM instance, by passing a reference to the textarea element to the fromTextArea method.

const editor = CodeMirror.fromTextArea(html.find("textarea")[0], { 
    mode: "javascript",             // A mode like "javascript" or "css"
    ...CodeMirror.userSettings,     // A special helper described later
    lineNumbers: true,              // CM has a number of settings you can configure
    inputStyle: "contenteditable",
    autofocus: true
});

This upgrades the textarea into a proper text editor.

CodeMirror "saves" the editor data back to the original textarea, however sometimes you need to explicitly tell it to save, such as immediately before submitting a form. This can be done by using the save() method on a CodeMirror instance. With the exampe above:

editor.save();

This will ensure that the textarea has the same content as the editor. It's good to call this at some point before you parse the data of the form, allowing you to retrieve the data from the textarea as normal.

Another option is to save on every change, by attaching an event handler to the CM object:

CodeMirror.fromTextArea(textarea, { 
    // options
}).on("change", (instance) => instance.save());

This may be less efficient for large inputs.

CodeMirror.userSettings

This special getter has been added to the CodeMirror object, it returns an object of settings retrieved from Foundry's module settings. This includes a few editor configurations like tab type and size, or word wrap. These settings can be passed along with other options when creating an instance of a CodeMirror editor. The simplest method is to use the ... spread operator to insert the key/value pairs of this object directly into the options:

CodeMirror.fromTextArea(textarea, { 
    mode: "css",
    ...CodeMirror.userSettings,
    lineNumbers: true, // etc.
})

This allows the user to configer editor preferences globally, while giving you a simple way to include those settings in your instance of the editor.