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

使用原生js自定义内置标签

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