highlight.js

需要的文件

<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/default.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/highlight.min.js"></script>

【示例】

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>

<body>
    <pre><code>
int main(){
  return 1;
}
    </code></pre>
    <pre><code>
window.onload = function() {
  let blocks = document.querySelectorAll("pre code");
  for (let i = 0, len = blocks.length; i < len; i++) {
    hljs.highlightBlock(blocks[i]);
  }
}
    </code></pre>
    <link rel="stylesheet" href="highlight.min.css">
    <script src="highlight.min.js"></script>
    <!-- 使用原生 JS 实现 -->
    <script>
    window.onload = function() {
        let blocks = document.querySelectorAll("pre code");
        for (let i = 0, len = blocks.length; i < len; i++) {
            hljs.highlightBlock(blocks[i]);
        }
    }
    </script>
    <!-- 使用 jQuery 实现 -->
    <!-- <script src="jquery-3.3.1.min.js"></script>
    <script>
    $(document).ready(function() {
        $('pre code').each(function(i, block) {
            hljs.highlightBlock(block);
        });
    });
    </script> -->
</body>

</html>