base/yu/index.html

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

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <img src="/image/o_74911.jpg" alt />
    <img src="/image/o_770659.jpg" alt />
    <img src="/image/o_899029.jpg" alt />
    <img src="/image/sh.jpg" alt />
    <img src="/image/PChome.gif" alt />
    <img src="/image/PCdetail.gif" alt />
    <img src="/image/PC1.jpg" />
    <img src="/image/PC2.jpg" />
    <img src="/image/PC3.jpg" />
</body>
<script>
    window.onload = function () {
        let imgs = document.querySelectorAll("img");
        let num = imgs.length;
        let count = 0;
        Array.from(imgs).forEach(item => {
            let img = new Image();
            img.onload = () => {
                count++; // 当count = num 时代表加载完成
            };
            img.src = item.getAttribute("src");
        });
    }
</script>

</html>