### Initialize Environment and Implement Back Navigation - JavaScript

Source: https://github.com/librespark/libretv/blob/main/player.html

This snippet initializes global variables for the application, including saving a reference to the original `sha256` function and setting up an environment object potentially populated by the server. It also provides a robust `goBack` function that attempts multiple strategies to navigate the user to the previous page, prioritizing URL parameters, localStorage, referrer, and parent window communication before falling back to `history.back()` or the homepage.

```JavaScript
// 保存原始 js‑sha256 实现，避免被 password.js 覆盖
window._jsSha256 = window.sha256;

// 创建全局环境变量对象
window.__ENV__ = window.__ENV__ || {};

// 注入服务器端环境变量 (将由服务器端替换)
// PASSWORD 变量将在这里被服务器端注入
window.__ENV__.PASSWORD = "{{PASSWORD}}";

// 改进返回上一页功能
function goBack(event) {
  // 防止默认链接行为
  if (event) event.preventDefault();

  // 1. 优先检查URL参数中的returnUrl
  const urlParams = new URLSearchParams(window.location.search);
  const returnUrl = urlParams.get('returnUrl');
  if (returnUrl) {
    // 如果URL中有returnUrl参数，优先使用
    window.location.href = decodeURIComponent(returnUrl);
    return;
  }

  // 2. 检查localStorage中保存的lastPageUrl
  const lastPageUrl = localStorage.getItem('lastPageUrl');
  if (lastPageUrl && lastPageUrl !== window.location.href) {
    window.location.href = lastPageUrl;
    return;
  }

  // 3. 检查是否是从搜索页面进入的播放器
  const referrer = document.referrer;
  // 检查 referrer 是否包含搜索参数
  if (referrer && (referrer.includes('/s=') || referrer.includes('?s='))) {
    // 如果是从搜索页面来的，返回到搜索页面
    window.location.href = referrer;
    return;
  }

  // 4. 如果是在iframe中打开的，尝试关闭iframe
  if (window.self !== window.top) {
    try {
      // 尝试调用父窗口的关闭播放器函数
      window.parent.closeVideoPlayer && window.parent.closeVideoPlayer();
      return;
    } catch (e) {
      console.error('调用父窗口closeVideoPlayer失败:', e);
    }
  }

  // 5. 无法确定上一页，则返回首页
  if (!referrer || referrer === '') {
    window.location.href = '/';
    return;
  }

  // 6. 以上都不满足，使用默认行为：返回上一页
  window.history.back();
}
```

--------------------------------

### Initialize Global Environment Variables (JavaScript)

Source: https://github.com/librespark/libretv/blob/main/index.html

Saves the original js-sha256 implementation to prevent conflicts and initializes a global environment variable object `__ENV__`, injecting a placeholder `{{PASSWORD}}` intended to be replaced by the server.

```JavaScript
// 保存原始 js‑sha256 实现，避免被 password.js 覆盖
window._jsSha256 = window.sha256;

// 创建全局环境变量对象
window.__ENV__ = window.__ENV__ || {};

// 注入服务器端环境变量 (将由服务器端替换)
// PASSWORD 变量将在这里被服务器端注入
window.__ENV__.PASSWORD = "{{PASSWORD}}";
```

--------------------------------

### Schema.org WebSite Markup (JSON-LD)

Source: https://github.com/librespark/libretv/blob/main/index.html

Defines the website using Schema.org's WebSite type, providing name, URL, description, and a potential search action for search engines to understand the site's structure and search capabilities.

```JSON-LD
{
  "@context": "https://schema.org",
  "@type": "WebSite",
  "name": "LibreTV",
  "url": "https://libretv.is-an.org/",
  "description": "免费在线视频搜索与观看平台",
  "potentialAction": {
    "@type": "SearchAction",
    "target": "https://libretv.is-an.org/?s={search\_term\_string}",
    "query-input": "required name=search\_term\_string"
  }
}
```

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