HN Blocklist Extension

background.js

browser.runtime.onMessage.addListener(async message => {
	const { param } = message;

	switch (param) {
		case "get":
			return getRecords();

		case "set":
			return setRecords(message.records);

		default:
			break;
	}
});

async function getRecords() {
	const { records = [] } = await browser.storage.local.get("records");
	return records;
}

async function setRecords(records) {
	await browser.storage.local.set({ records });
}

content_script.js

browser.runtime.sendMessage({ param: "get" }).then(records => {
	for (const { username, action } of records) {
		for (const usernameElement of document.querySelectorAll(`.hnuser[href$="=${ username }"]`)) {
			let defaultElement = usernameElement.parentElement.parentElement;
			while (!defaultElement.classList.contains("default")) {
				defaultElement = defaultElement.parentElement;
			}
			const commentElement = defaultElement.querySelector(".comment > .commtext");
			switch (action) {
				case "invisible":
					commentElement.style = "color: #f6f6ef;";
					break;

				case "flagged":
					commentElement.style = "color: #dddddd;";
					break;
			}
		}
	}
});

manifest.json

{
	"manifest_version": 2,
	"name": "HN Blocklist",
	"version": "1.0",
	"description": "Block users on HN",
	"applications": {
		"gecko": {
			"id": "extension-hn-blocklist@arnavion.dev"
		}
	},
	"background": {
		"scripts": ["background.js"],
		"persistent": false
	},
	"content_scripts": [{
		"matches": [ "https://news.ycombinator.com/*" ],
		"css": [],
		"js": [ "content_script.js" ],
		"run_at": "document_end",
		"all_frames": true
	}],
	"options_ui": {
		"page": "options.xhtml"
	},
	"permissions": [ "storage", "tabs", "https://news.ycombinator.com/*" ]
}

options.js

let recordsTbody;

addEventListener("DOMContentLoaded", () => {
	recordsTbody = document.getElementById("records");

	const saveRecordsButton = document.getElementById("save_records");
	saveRecordsButton.addEventListener("click", () => {
		saveRecordsButton.textContent = "Saving...";
		saveRecordsButton.disabled = true;

		const records = [];

		const trs = recordsTbody.getElementsByTagName("tr");
		for (const tr of recordsTbody.getElementsByTagName("tr")) {
			const [{ firstChild: { value: username } }, { firstChild: { value: action } }, { firstChild: { value: notes } }] = tr.children;
			if (username !== "" && (action !== "" || notes !== "")) {
				records.push({ username, action, notes });
			}
		}

		browser.runtime.sendMessage({ param: "set", records }).then(response => {
			prepareRecords();

			saveRecordsButton.textContent = "Save";
			saveRecordsButton.disabled = false;
		});
	});

	prepareRecords();
});

function prepareRecords() {
	while (recordsTbody.firstChild) {
		recordsTbody.removeChild(recordsTbody.firstChild);
	}

	browser.runtime.sendMessage({ param: "get" }).then(response => {
		for (const { username, action, notes } of response) {
			addNewRecordRow(username, action, notes);
		}

		addNewRecordRow("", null, "");
	});
}

function addNewRecordRow(username, action, notes) {
	const tr = document.createElement("tr");
	recordsTbody.appendChild(tr);

	{
		const td = document.createElement("td");
		tr.appendChild(td);

		const input = document.createElement("input");
		td.appendChild(input);
		input.type = "text";
		input.value = username;
	}

	{
		const td = document.createElement("td");
		tr.appendChild(td);

		const select = document.createElement("select");
		td.appendChild(select);

		const option1 = document.createElement("option");
		select.appendChild(option1);
		option1.value = "invisible";
		option1.innerText = "Invisible";

		const option2 = document.createElement("option");
		select.appendChild(option2);
		option2.value = "flagged";
		option2.innerText = "Flagged";

		switch (action) {
			case "invisible":
				select.value = "invisible";
				break;

			case "flagged":
				select.value = "flagged";
				break;

			default:
				break;
		}
	}

	{
		const td = document.createElement("td");
		tr.appendChild(td);

		const textArea = document.createElement("textarea");
		td.appendChild(textArea);
		textArea.rows = "1";
		textArea.cols = "20";
		textArea.value = notes;
	}

	{
		const td = document.createElement("td");
		tr.appendChild(td);

		const deleteButton = document.createElement("button");
		td.appendChild(deleteButton);
		deleteButton.appendChild(document.createTextNode("Delete"));
		deleteButton.addEventListener("click", () => recordsTbody.removeChild(tr));
	}
}

options.xhtml

<?xml version="1.0" encoding="utf-8"?>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
	<head>
		<title>HN Blocklist Options</title>
		<script src="options.js" />
	</head>
	<body>
		<table>
			<thead>
				<tr>
					<th>Username</th>
					<th>Action</th>
					<th>Notes</th>
				</tr>
			</thead>
			<tbody id="records">
			</tbody>
		</table>
		<div>
			<button id="save_records">Save</button>
		</div>
	</body>
</html>