Trilium/docs/Developer Guide/Developer Guide/Development and architecture/Options/Displaying the option in setti.md

Displaying the option in settings

Go to src/public/app/widgets/type_widgets/options and select a corresponding category, such as appearance and edit one of the JS files.

For example, to create a select:

First, modify the template (TPL), to add the new widget:

<div class="col-6">
    <label>First day of the week</label>
    <select class="first-day-of-week-select form-control">
        <option value="0">Sunday</option>
        <option value="1">Monday</option>
    </select>
</div>

Secondly, create a reference to the new element in doRender():

this.$firstDayOfWeek = this.$widget.find(".first-day-of-week-select");

Then in optionsLoaded adjust the value to the one set in the database:

this.$firstDayOfWeek.val(options.firstDayOfWeek);

To actually update the option, add a listener in doRender:

this.$firstDayOfWeek.on("change", () => {
    this.updateOption("firstDayOfWeek", this.$firstDayOfWeek.val());
});