原生JavaScript路由实现指南：History API与popstate事件详解

<html>
    <head>
        <title>Hello</title>
        <script type = "module">
            function select_tab(id) {
                // remove selected class from all buttons
                document.querySelectorAll(".route").forEach(item => item.classList.remove('selected'));
                // select clicked element (visually)
                document.querySelectorAll("#" + id).forEach(item => item.classList.add('selected'));
            }
            function load_content(id) {
                // Update text "Content loading for {id}..."
                // Of course, here you would do you content loading magic
                // Perhaps run Fetch API to update resources
                document.querySelector("#content").innerHTML = 'Content loading for /' + id + '...';
            }
            function push(event) {
                // Get id attribute of the box or button or link clicked
                let id = event.target.id;
                // Visually select the clicked button/tab/box
                select_tab(id);
                // Update Title in Window's Tab
                document.title = id;
                // Load content for this tab/page
                loadContent(id);
                // Finally push state change to the address bar
                window.history.pushState({id}, `${id}`, `/page/${id}`);
            }
            window.onload = event => {
                // Add history push() event when boxes are clicked
                window["home"].addEventListener("click", event => push(event))
                window["about"].addEventListener("click", event => push(event))
                window["gallery"].addEventListener("click", event => push(event))
                window["contact"].addEventListener("click", event => push(event))
                window["help"].addEventListener("click", event => push(event))
            }
            // Listen for PopStateEvent (Back or Forward buttons are clicked)
            window.addEventListener("popstate", event => {
                // Grab the history state id
                let stateId = event.state.id;
                // Show clicked id in console (just for fun)
                console.log("stateId = ", stateId);
                // Visually select the clicked button/tab/box
                select_tab(stateId);
                // Load content for this tab/page
                loadContent(id);
            });
        </script>
        <style>
            * { /* global font */
                font-family: Verdana;
                font-size: 18px;
            }
            #root { display: flex; flex-direction: row; }
            #content { display: flex;
                display: block;
                width: 800px;
                height: 250px;
                /* vertically centered text */
                line-height: 250px;
                border: 2px solid #555;
                margin: 32px;
                text-align: center;
            }
            .route {
                cursor: pointer;
                justify-content: center;
                width: 150px;
                height: 50px;
                /* vertically centered text */
                line-height: 50px;
                position: relative;
                border: 2px solid #555;
                background: white;
                text-align: center;
                margin: 16px;
            }
            .route.selected { background: yellow; }
        </style>
    </head>

    <body>

        <section id = "root">
            <section class = "route" id = "home">/home</section>
            <section class = "route" id = "about">/about</section>
            <section class = "route" id = "gallery">/gallery</section>
            <section class = "route" id = "contact">/contact</section>
            <section class = "route" id = "help">/help</section>
        </section>

        <main id = "content">Content loading...</main>
    
    </body>

</html>