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4chan Base64 Decode Tool

appears in the thread page. auto recursive decoding if the message is coded multiple times.

您需要先安装一款用户脚本管理器扩展,例如 Tampermonkey 篡改猴Greasemonkey 油猴子Violentmonkey 暴力猴,才能安装此脚本。

您需要先安装一款用户脚本管理器扩展,例如 Tampermonkey 篡改猴,才能安装此脚本。

您需要先安装一款用户脚本管理器扩展,例如 Tampermonkey 篡改猴Violentmonkey 暴力猴,才能安装此脚本。

您需要先安装一款用户脚本管理器扩展,例如 Tampermonkey 篡改猴Userscripts ,才能安装此脚本。

您需要先安装一款用户脚本管理器扩展,例如 Tampermonkey 篡改猴,才能安装此脚本。

您需要先安装一款用户脚本管理器扩展后才能安装此脚本。

(我已经安装了用户脚本管理器,让我安装!)

您需要先安装一款用户样式管理器扩展,比如 Stylus,才能安装此样式。

您需要先安装一款用户样式管理器扩展,比如 Stylus,才能安装此样式。

您需要先安装一款用户样式管理器扩展,比如 Stylus,才能安装此样式。

您需要先安装一款用户样式管理器扩展后才能安装此样式。

您需要先安装一款用户样式管理器扩展后才能安装此样式。

您需要先安装一款用户样式管理器扩展后才能安装此样式。

(我已经安装了用户样式管理器,让我安装!)

// ==UserScript==
// @name         4chan Base64 Decode Tool
// @namespace    https://github.com/x94fujo6rpg/SomeTampermonkeyScripts
// @version      0.01
// @description  appears in the thread page. auto recursive decoding if the message is coded multiple times.
// @author       x94fujo6
// @match        https://boards.4chan.org/*/thread/*
// @match        https://boards.4channel.org/*/thread/*
// ==/UserScript==
/* jshint esversion: 9 */

(function () {
	let
		elem = {
			tool: "decode_tool",
			in: "decode_input",
			out: "decode_output",
			decode: "decode_shit",
			copy: "decode_copy",
			open: "decode_open",
			close: "decode_close",
		},
		box = document.createElement("div"),
		class_list = {
			title: "usTitle",
			box: "usBox",
			t: "usTextBox",
			b: "usButton line-2-item",
		},
		getIn = () => document.getElementById(elem.in).value,
		getOut = () => document.getElementById(elem.out).value,
		setIn = (t = "") => document.getElementById(elem.in).value = t,
		setOut = (t = "") => document.getElementById(elem.out).value = t,
		decode_text = () => {
			let text = getIn(),
				count = 0,
				max = 100,
				[err, output] = decoder(text),
				last_output = output,
				err_msg = "decode failed";
			setIn();
			console.log(count, text);
			if (err) {
				setOut(err_msg);
				console.log(err_msg);
			}
			while (!err && output.length && count < max) {
				count++;
				console.log(count, last_output);
				setOut(last_output);
				[err, output] = decoder(last_output);
				if (err) {
					console.log("end loop");
					break;
				} else {
					setIn(last_output);
					last_output = output;
				}
			}

			function decoder(_t = "") {
				let out = false,
					error = false;
				try {
					out = atob(_t);
				} catch (e) {
					error = e;
				} finally {
					return [error, out];
				}
			}
		},
		copy = () => {
			let text = document.getElementById(elem.out);
			text.select();
			text.setSelectionRange(0, 99999);
			document.execCommand("copy");
		},
		open = () => document.getElementById(elem.tool).style.display = "",
		close = () => document.getElementById(elem.tool).style.display = "none";

	box.className = class_list.box;
	box.innerHTML = `
		<div class="${class_list.title}">Base64 Decode Tool</div>
		<div id="${elem.tool}" style="display: none;">
			<button type="button" id="${elem.decode}" class="${class_list.b}">Decode Input</button>
			<button type="button" id="${elem.copy}" class="${class_list.b}">Copy Output</button>
			<textarea id="${elem.in}" class="${class_list.t}" rows="10" cols="70" placeholder="input"></textarea>
			<textarea id="${elem.out}" class="${class_list.t}" rows="10" cols="70" placeholder="output"></textarea>
		</div>
		<button type="button" id="${elem.open}" class="${class_list.b}">Open</button>
		<button type="button" id="${elem.close}" class="${class_list.b}">Close</button>
	`;
	addCss();
	document.body.appendChild(box);
	document.getElementById(elem.decode).onclick = () => decode_text(false);
	document.getElementById(elem.copy).onclick = () => copy();
	document.getElementById(elem.open).onclick = () => open();
	document.getElementById(elem.close).onclick = () => close();

	function addCss() {
		let s = document.createElement("style");
		document.head.appendChild(s);
		s.textContent = `
			.usTitle {
				display: block;
				font-size: large;
				margin: auto;
				width: 20rem;
				padding: 0.5rem;
			}

			.usBox {
				position: fixed;
				bottom: 1rem;
				right: 1rem;
				z-index: 100;
				border: 2px ridge rgba(0, 0, 0, 0.3);
				background-color: rgba(255, 255, 255, 0.75);
				display: block;
				width: max-content;
				height: max-content;
				text-align: center;
			}

			.usTextBox {
				display: flex;
				width: 95%;
				height: 35%;
				margin: 0.2rem auto;
				word-break: break-all;
			}

			.usButton {
				display: inline;
				margin: 0.25rem;
				padding: 0.5rem;
				text-align: center;
				font-size: large;
			}

			.line-2-item {
				max-width: 100%;
				width: calc(90% / 2);
			}
		`;
	}
})();