鉴于坛里base64编码内容越来越多，vibe了一个简单的油猴脚本

功能很简单，就是编码解码，支持多轮编码解码，支持一键复制，

使用方法：右键-Tampermonkey-Base64编解码助手，欢迎佬友们继续完善。

// ==UserScript==

// @name         Base64 编解码助手

// @namespace    https://github.com/mikylu

// @version      1.0

// @description  选中文字进行 Base64 编码/解码，支持反复再次操作

// @author       城市猎人

// @match        *://*/*

// @grant        GM_registerMenuCommand

// @grant        GM_setClipboard

// @run-at       document-start

// ==/UserScript==



(function () {

  'use strict';



  const STYLE = `

    #b64-overlay{position:fixed;top:0;left:0;width:100%;height:100%;z-index:2147483646}

    #b64-modal{position:fixed;top:50%;left:50%;transform:translate(-50%,-50%);

      background:#fff;border-radius:12px;box-shadow:0 8px 32px rgba(0,0,0,.25);

      padding:24px 28px;min-width:360px;max-width:560px;z-index:2147483647;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif}

    #b64-modal .b64-round{font-size:13px;color:#888;margin-bottom:8px}

    #b64-modal .b64-result{background:#f5f5f5;border:1px solid #e0e0e0;border-radius:8px;

      padding:12px 14px;word-break:break-all;max-height:240px;overflow-y:auto;font-size:14px;

      line-height:1.6;color:#333;white-space:pre-wrap;user-select:text}

    #b64-modal .b64-actions{display:flex;gap:10px;margin-top:16px;justify-content:flex-end}

    #b64-modal .b64-btn{border:none;border-radius:8px;padding:8px 20px;font-size:14px;

      cursor:pointer;transition:opacity .15s}

    #b64-modal .b64-btn:hover{opacity:.85}

    #b64-modal .b64-btn-primary{background:#1677ff;color:#fff}

    #b64-modal .b64-btn-secondary{background:#f0f0f0;color:#333}

    #b64-modal .b64-btn-close{background:#f5f5f5;color:#999}

    #b64-modal .b64-err{color:#ff4d4f;font-size:13px;margin-top:8px}

    #b64-modal .b64-copied{color:#52c41a;font-size:13px;margin-top:8px;display:none}

  `;



  const LABELS = {

    decode: { action: '解码', again: '再次解码' },

    encode: { action: '编码', again: '再次编码' },

  };



  function injectStyle() {

    if (document.getElementById('b64-style')) return;

    const s = document.createElement('style');

    s.id = 'b64-style';

    s.textContent = STYLE;

    (document.head || document.documentElement).appendChild(s);

  }



  function removeModal() {

    document.getElementById('b64-overlay')?.remove();

    document.getElementById('b64-modal')?.remove();

  }



  function tryTransform(text, mode) {

    if (mode === 'decode') {

      try {

        return { ok: true, value: decodeURIComponent(atob(text)) };

      } catch {

        try {

          return { ok: true, value: atob(text) };

        } catch {

          return { ok: false };

        }

      }

    } else {

      try {

        return { ok: true, value: btoa(unescape(encodeURIComponent(text))) };

      } catch {

        return { ok: false };

      }

    }

  }



  function showModal(round, text, mode) {

    removeModal();

    injectStyle();

    const L = LABELS[mode];



    const overlay = document.createElement('div');

    overlay.id = 'b64-overlay';

    overlay.addEventListener('click', removeModal);



    const modal = document.createElement('div');

    modal.id = 'b64-modal';

    modal.addEventListener('click', (e) => e.stopPropagation());



    const roundLabel = document.createElement('div');

    roundLabel.className = 'b64-round';

    roundLabel.textContent = `第 ${round} 次${L.action}`;



    const resultBox = document.createElement('div');

    resultBox.className = 'b64-result';

    resultBox.textContent = text;



    const copiedHint = document.createElement('div');

    copiedHint.className = 'b64-copied';

    copiedHint.textContent = '✓ 已复制到剪贴板';



    const actions = document.createElement('div');

    actions.className = 'b64-actions';



    const btnCopy = document.createElement('button');

    btnCopy.className = 'b64-btn b64-btn-primary';

    btnCopy.textContent = '复制结果';

    btnCopy.addEventListener('click', () => {

      GM_setClipboard(text, 'text');

      copiedHint.style.display = 'block';

      setTimeout(() => (copiedHint.style.display = 'none'), 1500);

    });



    const btnAgain = document.createElement('button');

    btnAgain.className = 'b64-btn b64-btn-secondary';

    btnAgain.textContent = L.again;

    btnAgain.addEventListener('click', () => {

      const next = tryTransform(text, mode);

      if (next.ok) {

        showModal(round + 1, next.value, mode);

      } else {

        resultBox.style.borderColor = '#ffccc7';

        roundLabel.textContent = `第 ${round + 1} 次${L.action}失败`;

        const errHint = document.createElement('div');

        errHint.className = 'b64-err';

        errHint.textContent = mode === 'decode'

          ? '当前内容不是有效的 Base64，无法继续解码'

          : '当前内容编码失败';

        modal.appendChild(errHint);

        btnAgain.disabled = true;

        btnAgain.style.opacity = '0.4';

        btnAgain.style.cursor = 'not-allowed';

      }

    });



    const btnClose = document.createElement('button');

    btnClose.className = 'b64-btn b64-btn-close';

    btnClose.textContent = '关闭';

    btnClose.addEventListener('click', removeModal);



    actions.append(btnCopy, btnAgain, btnClose);

    modal.append(roundLabel, resultBox, copiedHint, actions);

    document.body.append(overlay, modal);

  }



  function showError(msg) {

    injectStyle();

    removeModal();

    const overlay = document.createElement('div');

    overlay.id = 'b64-overlay';

    overlay.addEventListener('click', removeModal);

    const modal = document.createElement('div');

    modal.id = 'b64-modal';

    modal.innerHTML = `<div class="b64-err">${msg}</div>

      <div class="b64-actions"><button class="b64-btn b64-btn-close" id="b64-close-only">关闭</button></div>`;

    document.body.append(overlay, modal);

    modal.querySelector('#b64-close-only').addEventListener('click', removeModal);

  }



  document.addEventListener('keydown', (e) => {

    if (e.key === 'Escape') removeModal();

  });



  function startAction(mode) {

    const L = LABELS[mode];

    const selectedText = (window.getSelection?.() || '').toString().trim();

    if (!selectedText) {

      showError('请先选中文字，再点击菜单进行' + L.action);

      return;

    }

    const result = tryTransform(selectedText, mode);

    if (result.ok) {

      showModal(1, result.value, mode);

    } else {

      injectStyle();

      removeModal();

      const overlay = document.createElement('div');

      overlay.id = 'b64-overlay';

      overlay.addEventListener('click', removeModal);

      const modal = document.createElement('div');

      modal.id = 'b64-modal';

      modal.innerHTML = `<div class="b64-round">第 1 次${L.action}失败</div>

        <div class="b64-err">选中的文字不是有效的 Base64</div>

        <div class="b64-actions"><button class="b64-btn b64-btn-close" id="b64-close-only">关闭</button></div>`;

      document.body.append(overlay, modal);

      modal.querySelector('#b64-close-only').addEventListener('click', removeModal);

    }

  }



  GM_registerMenuCommand('Base64 解码', () => startAction('decode'));

  GM_registerMenuCommand('Base64 编码', () => startAction('encode'));

})();