github-issue-to-branch-name.js

javascript: (function() {
	let repoName;
	if (document.querySelectorAll('.public .author').length !== 0) {
		repoName = document.querySelectorAll('.public .author')[0].textContent;
	} else if (document.querySelectorAll('.private .author').length !== 0) {
		repoName = document.querySelectorAll('.private .author')[0].textContent;
	}
	let repoAuthor = document.querySelectorAll('.gh-header-meta .author')[0].textContent;

	let issueNumber = document.querySelectorAll('.gh-header-number')[0].textContent;
	
	issueNumber = issueNumber.replace('#', '');

	const title = document.querySelectorAll('.js-issue-title')[0].textContent.trim();

	const replacements = [
		{name: 'mdot', replacement: ['·', '']},
		{name: 'dot', replacement: [/\./g, '']},
		{name: 'midDot', replacement: [/%C2%B7/g, '']},
		{name: 'spaceMidDot', replacement: [' %C2%B7 ', '']},
		{name: 'author', replacement: [repoAuthor + '\/', '']},
		{name: 'repoName', replacement: [repoName, '']},
		{name: 'issueNum', replacement: ['Issue #', '']},
		{name: 'rBracketSpace', replacement: ['] ', '___']},
		{name: 'ampSpace', replacement: [/ \& /g, '_and_']},
		{name: 'amp', replacement: [/\&/g, '/']},
		{name: 'comma', replacement: [/,/g, '_']},
		{name: 'colSpace', replacement: [/: /g, '--']},
		{name: 'col', replacement: [/:/g, '--']},
		{name: 'dashSpace', replacement: [/ %E2%80%93 /g, '--']},
		{name: 'mdashSpace', replacement: [/ %E2%80%94 /g, '---']},
		{name: 'dash', replacement: [/%E2%80%93/g, '--']},
		{name: 'mdash', replacement: [/%E2%80%94/g, '---']},
		{name: 'slash', replacement: [/\//g, '_or_']},
		{name: 'percent', replacement: [/\%/g, '-percent']},
		{name: 'quot', replacement: [/\"/g, '']},
		{name: 'squot', replacement: [/\'/g, '']},
		{name: 'tick', replacement: [/`/g, '']},
		{name: 'lquot', replacement: [/%E2%80%9C/g, '']},
		{name: 'rquot', replacement: [/%E2%80%9D/g, '']},
		{name: 'lsquot', replacement: [/%E2%80%98/g, '']},
		{name: 'rsquot', replacement: [/%E2%80%99/g, '']},
		{name: 'lparen', replacement: [/\(/g, '']},
		{name: 'rparen', replacement: [/\)/g, '']},
		{name: 'lstash', replacement: [/\{/g, '']},
		{name: 'rstash', replacement: [/\}/g, '']},
		{name: 'lbracket', replacement: [/\[/g, '']},
		{name: 'rbracket', replacement: [/\]/g, '']},
		{name: 'at', replacement: [/@/g, '']},
		{name: 'dolladolla', replacement: [/\$/g, '']},
		{name: 'star', replacement: [/\*/g, '']},
		{name: 'pound', replacement: [/\#/g, '']},
		{name: 'bang', replacement: [/\!/g, '']},
		{name: 'parendash', replacement: [/^([a-z0-9])-/i, '$1-']},
		{name: 'space', replacement: [/ /g, '-']},
		{name: 'dishuedash', replacement: ['--' + issueNumber + '--', '']},
		{name: 'dishue', replacement: ['--' + issueNumber, '']},
	];

	let filteredTitle = title;
	replacements.forEach((r) => {
		filteredTitle = filteredTitle.replace(r.replacement[0], r.replacement[1]);
	});

	const formattedTitle = 'GH' + issueNumber + '---' + filteredTitle.toLowerCase() || "would-be-a-title-if-there-was-one";


	function promptForCopyToClipboard(text) {
		window.prompt("Copy:", text);
	}

	let newDivForCopy = document.createElement("div");
	let newContent = document.createTextNode(formattedTitle);
	newDivForCopy.appendChild(newContent);
	let showIssueDiv = document.getElementsByTagName('body')[0];
	let newChildForCopying = showIssueDiv.appendChild(newDivForCopy);
	let range = document.createRange();
	range.selectNode(newChildForCopying);
	window.getSelection().addRange(range);
	try {
		let successful = document.execCommand('copy');
		let msg = successful ? 'successful' : 'unsuccessful';
		console.log(`Copied new GitHub branch (${formattedTitle}) to clipboard.`);
	} catch (err) {
		console.log('Oops, unable to copy automatically, opening prompt.');
		promptForCopyToClipboard(formattedTitle);
	}
	window.getSelection().removeAllRanges();
})();

started cleaning up the code but ran out of time half way through. It's working at least.