joplin/packages/app-mobile/MarkdownEditor/applyWrapFormatNewLines.js

import { replaceBetween } from './utils';
const shim = require('@joplin/lib/shim').default;

export default ({ getState, item, setState }) => {
	const { text, selection } = getState();
	let newText = replaceBetween(
		text,
		selection,
		`\n${item.wrapper.concat(
			'\n',
			text.substring(selection.start, selection.end),
			'\n',
			item.wrapper,
			'\n'
		)}`
	);
	let newPosition;
	if (selection.start === selection.end) {
		newPosition = selection.end + item.wrapper.length + 2; // +2 For two new lines
		newText = replaceBetween(
			text,
			selection,
			`\n${item.wrapper.concat(
				'\n',
				text.substring(selection.start, selection.end),
				'\n',
				item.wrapper,
				'\n'
			)}`
		);
	} else {
		newPosition = selection.end + item.wrapper.length * 2 + 3; // +3 For three new lines
		newText = replaceBetween(
			text,
			selection,
			`${item.wrapper.concat(
				'\n',
				text.substring(selection.start, selection.end),
				'\n',
				item.wrapper,
				'\n'
			)}`
		);
	}
	const extra = {
		selection: {
			start: newPosition,
			end: newPosition,
		},
	};
	setState({ text: newText }, () => {
		shim.setTimeout(() => {
			setState({ ...extra });
		}, 25);
	});
};