使用原生js自定义内置标签

2024-01-31 12:20:16
使用原生js自定义内置标签

效果图
代码
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <article contenteditable="" id="textbox">
        我是文字
    </article>

    <p is="word-count"></p>
</body>
<script>
    class WordCount extends HTMLParagraphElement {
        constructor() {
            super();

            var wc = document.getElementById("textbox");

            function countWords(node) {
                var text = node.innerText || node.textContent
                console.log(text, text.length)
                return text.length;
            }
            var count = '字数: ' + countWords(wc);

            // 创建影子节点
            var shadow = this.attachShadow({ mode: 'open' });

            // 创建要给span标签，展示文字个数
            var text = document.createElement('span');
            text.setAttribute('class', 'text');
            text.textContent = count;

            var style = document.createElement('style');
            style.textContent = 
            `
                .text{
                    color: green;
                    font-size: 25px;
                }
            `

            // 将文字添加到影子节点中
            shadow.appendChild(style);
            shadow.appendChild(text);


            // Update count when element content changes
            setInterval(function () {
                var count = '字数: ' + countWords(wc);
                text.textContent = count;
            }, 200)

        }
    }

    // Define the new element
    customElements.define('word-count', WordCount, { extends: 'p' });

</script>

</html>
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使用原生js自定义内置标签

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