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HTML

              
                <!DOCTYPE html>
<html lang="zh-Hans">

<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">
    <meta name="author" content="xgqfrms">
    <meta name="generator" content="VS code">
    <title>Mutation Observer & customize resize event listener & demo</title>
    <style>
        ol {
            box-sizing: border-box;
            width: 110px;
            height: 110px;
            border: 1px solid red;
            padding: 10px;
            resize: both;
            overflow: auto;
        }
    </style>
</head>

<body>
    <section>
        <h1>Mutation Observer & customize resize event listener & demo</h1>
    </section>
    <section>
        <ol contenteditable oninput="">
            <li>Press enter</li>
        </ol>
    </section>
    <!-- js -->
    <script>
        const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
        // target
        const list = document.querySelector(`ol`);
        // options
        const config = {
            attributes: true,
            childList: true,
            characterData: true,
            subtree: true,
        };
        // instance
        const observer = new MutationObserver(function(mutations) {
            // console.log(`mutations =`, mutations); // MutationRecord
            mutations.forEach(function(mutation) {
                // console.log("mutation =", mutation);
                if (mutation.type === "characterData") {
                    // target & object === typeof(mutation.target)
                    // console.log("A child node has been added OR removed.", mutation.target, typeof(mutation.target));
                    // console.log("[...mutation.addedNodes].length", [...mutation.addedNodes].length);
                    // console.log("[...mutation.removedNodes].length", [...mutation.removedNodes].length);
                    // if (mutation.target && [...mutation.addedNodes].length) {
                    //     // [...mutation.addedNodes].length
                    //     console.log(`A child node ${mutation.target} has been added!`, mutation.target);
                    // }
                    // if (mutation.target && [...mutation.removedNodes].length) {
                    //     // [...mutation.removedNodes].length
                    //     console.log(`A child node ${mutation.target} has been removed!`, mutation.target);
                    // }
                }
                if (mutation.type === "childList") {
                    if (mutation.target && [...mutation.addedNodes].length) {
                        console.log(`A child node ${mutation.target} has been added!`, mutation.target);
                    }
                    if (mutation.target && [...mutation.removedNodes].length) {
                        console.log(`A child node ${mutation.target} has been removed!`, mutation.target);
                    }
                    // do somwthings
                    let list_values = [];
                    list_values = [].slice.call(list.children).map(function(node) {
                        return node.innerHTML;
                    }).filter(function(str) {
                        if (str === "<br>") {
                            return false;
                        } else {
                            return true;
                        }
                    });
                    console.log(list_values);
                }
                if (mutation.type === "attributes") {
                    console.log("mutation =", mutation);
                    console.log(`The \`${mutation.attributeName}\` attribute was modified.`);
                    // console.log("list style =", list.style);
                    let {
                        width,
                        height,
                    } = list.style;
                    let style = {
                        width,
                        height
                    };
                    console.log("style =\n", JSON.stringify(style, null, 4));
                }
            });
        });
        observer.observe(list, config);
        // Later, you can stop observing
        // setTimeout(() => {
        //     observer.disconnect();
        // }, 1000 * 100);
        // bug ??? after disconnect
        // list.attributes;
        // list.setAttribute(`style`, `height: 212px; width: 213px;`);
        // list.setAttribute(`data-test`, `666`);
        // list.removeAttribute(`data-test`);
        // list.children;
        // list.childElementCount;
        // list.childNodes;
        // list.hasChildNodes();
        // list.firstElementChild;
        // list.firstChild;
        // list.removeChild(li);
        // list.removeChild(list.firstElementChild);
        // list.replaceChild(li, li);
        // list.replaceChild(list.firstElementChild, list.lastElementChild);
    </script>
</body>

</html>
              
            
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JS

              
                
              
            
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