Convert a list of 10 colors to a Firefox theme manifest.

generate-theme.js

// Convert a list of 10 colors (eg. generated by https://primer.style/prism/)
// to a Firefox theme manifest.
//
// name: The name of the theme.
// colors: An array of 10 colors.
// id: The ID of the theme. Format: "your-add-on-name@your-domain.com".
// version (optional): The version of the theme. Format: "<major>.<minor>".
//
// Docs: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme
//
// To use the manifest, save the output as `manifest.json`, zip it, change the
// file extension to `.xpi`, and drag it into Firefox.
function generateTheme(name, colors, id, version = '1.0') {
	if (!name || !colors || !id) throw new Error('Error: `name`, `colors`, and `id` are required arguments.');

	return JSON.stringify(
		{
			name,
			manifest_version: 2,
			version,
			theme: {
				images: {},
				properties: {},
				colors: {
					button_background_active: colors[3],
					frame_inactive: colors[8],
					frame: colors[9],
					icons_attention: colors[1],
					icons: colors[2],
					ntp_background: colors[9],
					ntp_text: colors[3],
					popup_border: colors[6],
					popup_highlight_text: colors[0],
					popup_highlight: colors[4],
					popup_text: colors[0],
					popup: colors[6],
					sidebar_border: colors[6],
					sidebar_highlight_text: colors[0],
					sidebar_highlight: colors[7],
					sidebar_text: colors[1],
					sidebar: colors[9],
					tab_background_text: colors[2],
					tab_line: colors[7],
					tab_loading: colors[7],
					tab_selected: colors[7],
					tab_text: colors[0],
					toolbar_field_border_focus: 'transparent',
					toolbar_field_focus: colors[7],
					toolbar_field_highlight: colors[5],
					toolbar_field_text: colors[0],
					toolbar_field: colors[8],
					toolbar_text: colors[2],
					toolbar: 'transparent',
				},
			},
			browser_specific_settings: {
				gecko: {
					id,
				},
			},
		},
		null,
		'\t'
	);
}

// Example usage:
generateTheme(
	'Dim',
	['#f5f1f3', '#c8c2c5', '#989295', '#6e6c6d', '#504f50', '#3a3a3a', '#2c2c2c', '#222223', '#1c1b1e', '#19181c'],
	version
);