网页平板签名捕获问题：签名区域无法显示求助

Hey there! Let's walk through the most likely issues causing your signature capture area not to render properly, along with fixes you can try right away:

1. Local Resource Path Mismatch (Top Culprit) #

The biggest red flag in your code is the paths for the signature plugin's CSS and JS files:

<link href="/usr/share/javascript/jquery/jquery.signature.css" rel="stylesheet">
<script src="/usr/share/javascript/jquery/jquery.signature.js"></script>

These are system-level file paths, not paths relative to your web project. Browsers can't access files directly from your server's (or local machine's) filesystem like this—they'll return a 404 error for these resources, meaning the signature plugin never loads.

Fix: #

Download the jquery.signature.css and jquery.signature.js files to your project directory (create css/ and js/ folders if you don't have them), then update the paths to be relative to your HTML file:

<link href="css/jquery.signature.css" rel="stylesheet">
<script src="js/jquery.signature.js"></script>

2. Outdated CDN Compatibility #

You're using older versions of jQuery (1.12.4) and jQuery UI (1.12.1). While they might work, newer stable versions are more reliable and less likely to have compatibility gaps with the signature plugin.

Fix: #

Swap your CDN links for these more recent versions (still compatible with most use cases):

<script src="https://code.jquery.com/jquery-3.6.4.min.js"></script>
<script src="https://code.jquery.com/ui/1.13.2/jquery-ui.min.js"></script>
<link href="https://code.jquery.com/ui/1.13.2/themes/south-street/jquery-ui.css" rel="stylesheet">

3. Use Browser DevTools to Diagnose #

As a beginner, the browser's developer tools are your best friend for debugging issues like this:

• Press F12 to open DevTools, then go to the Network tab. Refresh your page—look for any resources marked in red (these failed to load).
• Check the Console tab for error messages:
  • $ is not defined: jQuery didn't load correctly
  • signature is not a function: The signature plugin didn't load (usually due to path issues)

4. Local File Protocol Restrictions #

If you're opening your HTML file directly (via file:// in the browser), some browsers block CDN resource loading for security reasons.

Fix: #

Run a local static server to serve your files:

• For Python 3: Open your project folder in terminal and run python -m http.server
• For Node.js: Install http-server with npm install -g http-server, then run http-server in your project folder
  Then access your page via http://localhost:8000 (or the port shown in the terminal).

Bonus: Simplify for Debugging #

The excanvas.js script is only for old IE browsers. If you don't need to support IE, remove that conditional comment temporarily to rule out any issues with it.

内容的提问来源于stack exchange，提问作者Simon King