Ajax navigation example

这是一个仅由三个页面组成的 AJAX 网站示例 (first_page.php, second_page.php and third_page.php). 要查看其如何工作的，请创建以下文件 (或 git clone https://github.com/giabao/mdn-ajax-nav-example.git ):

备注： 为了在该机制中很好地整合<form>元素 , 请看一下这段 Submitting forms and uploading files。

first_page.php:

<?php
    $page_title = "First page";

    $as_json = false;
    if (isset($_GET["view_as"]) && $_GET["view_as"] == "json") {
        $as_json = true;
        ob_start();
    } else {
?>
<!doctype html>
<html>
<head>
<?php
        include "include/header.php";
        echo "<title>" . $page_title . "</title>";
?>
</head>

<body>

<?php include "include/before_content.php"; ?>

<p>This paragraph is shown only when the navigation starts from <strong>first_page.php</strong>.</p>

<div id="ajax-content">
<?php } ?>

    <p>This is the content of <strong>first_page.php</strong>.</p>

<?php
    if ($as_json) {
        echo json_encode(array("page" => $page_title, "content" => ob_get_clean()));
    } else {
?>
</div>

<p>This paragraph is shown only when the navigation starts from <strong>first_page.php</strong>.</p>

<?php
        include "include/after_content.php";
        echo "</body>\n</html>";
    }
?>

second_page.php:

<?php
    $page_title = "Second page";

    $as_json = false;
    if (isset($_GET["view_as"]) && $_GET["view_as"] == "json") {
        $as_json = true;
        ob_start();
    } else {
?>
<!doctype html>
<html>
<head>
<?php
        include "include/header.php";
        echo "<title>" . $page_title . "</title>";
?>
</head>

<body>

<?php include "include/before_content.php"; ?>

<p>This paragraph is shown only when the navigation starts from <strong>second_page.php</strong>.</p>

<div id="ajax-content">
<?php } ?>

    <p>This is the content of <strong>second_page.php</strong>.</p>

<?php
    if ($as_json) {
        echo json_encode(array("page" => $page_title, "content" => ob_get_clean()));
    } else {
?>
</div>

<p>This paragraph is shown only when the navigation starts from <strong>second_page.php</strong>.</p>

<?php
        include "include/after_content.php";
        echo "</body>\n</html>";
    }
?>

third_page.php:

<?php
    $page_title = "Third page";
    $page_content = "<p>This is the content of <strong>third_page.php</strong>. This content is stored into a php variable.</p>";

    if (isset($_GET["view_as"]) && $_GET["view_as"] == "json") {
        echo json_encode(array("page" => $page_title, "content" => $page_content));
    } else {
?>
<!doctype html>
<html>
<head>
<?php
        include "include/header.php";
        echo "<title>" . $page_title . "</title>";
?>
</head>

<body>

<?php include "include/before_content.php"; ?>

<p>This paragraph is shown only when the navigation starts from <strong>third_page.php</strong>.</p>

<div id="ajax-content">
<?php echo $page_content; ?>
</div>

<p>This paragraph is shown only when the navigation starts from <strong>third_page.php</strong>.</p>

<?php
        include "include/after_content.php";
        echo "</body>\n</html>";
    }
?>

css/style.css:

#ajax-loader {
    position: fixed;
    display: table;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

#ajax-loader > div {
    display: table-cell;
    width: 100%;
    height: 100%;
    vertical-align: middle;
    text-align: center;
    background-color: #000000;
    opacity: 0.65;
}

include/after_content.php:

<p>This is the footer. It is shared between all ajax pages.</p>

include/before_content.php:

<p>
[ <a class="ajax-nav" href="first_page.php">First example</a>
| <a class="ajax-nav" href="second_page.php">Second example</a>
| <a class="ajax-nav" href="third_page.php">Third example</a>
| <a class="ajax-nav" href="unexisting.php">Unexisting page</a> ]
</p>

include/header.php:

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script type="text/javascript" src="js/ajax_nav.js"></script>
<link rel="stylesheet" href="css/style.css" />

js/ajax_nav.js:

"use strict";

const ajaxRequest = new (function () {

    function closeReq () {
        oLoadingBox.parentNode && document.body.removeChild(oLoadingBox);
        bIsLoading = false;
    }

    function abortReq () {
        if (!bIsLoading) { return; }
        oReq.abort();
        closeReq();
    }

    function ajaxError () {
        alert("Unknown error.");
    }

    function ajaxLoad () {
        var vMsg, nStatus = this.status;
        switch (nStatus) {
            case 200:
                vMsg = JSON.parse(this.responseText);
                document.title = oPageInfo.title = vMsg.page;
                document.getElementById(sTargetId).innerHTML = vMsg.content;
                if (bUpdateURL) {
                    history.pushState(oPageInfo, oPageInfo.title, oPageInfo.url);
                    bUpdateURL = false;
                }
                break;
            default:
                vMsg = nStatus + ": " + (oHTTPStatus[nStatus] || "Unknown");
                switch (Math.floor(nStatus / 100)) {
                    /*
                    case 1:
                        // Informational 1xx
                        console.log("Information code " + vMsg);
                        break;
                    case 2:
                        // Successful 2xx
                        console.log("Successful code " + vMsg);
                        break;
                    case 3:
                        // Redirection 3xx
                        console.log("Redirection code " + vMsg);
                        break;
                    */
                    case 4:
                        /* Client Error 4xx */
                        alert("Client Error #" + vMsg);
                        break;
                    case 5:
                        /* Server Error 5xx */
                        alert("Server Error #" + vMsg);
                        break;
                    default:
                        /* Unknown status */
                        ajaxError();
                }
        }
        closeReq();
    }

    function filterURL (sURL, sViewMode) {
        return sURL.replace(rSearch, "") + ("?" + sURL.replace(rHost, "&").replace(rView, sViewMode ? "&" + sViewKey + "=" + sViewMode : "").slice(1)).replace(rEndQstMark, "");
    }

    function getPage (sPage) {
        if (bIsLoading) { return; }
        oReq = new XMLHttpRequest();
        bIsLoading = true;
        oReq.onload = ajaxLoad;
        oReq.onerror = ajaxError;
        if (sPage) { oPageInfo.url = filterURL(sPage, null); }
        oReq.open("get", filterURL(oPageInfo.url, "json"), true);
        oReq.send();
        oLoadingBox.parentNode || document.body.appendChild(oLoadingBox);
    }

    function requestPage (sURL) {
        if (history.pushState) {
            bUpdateURL = true;
            getPage(sURL);
        } else {
            /* Ajax navigation is not supported */
            location.assign(sURL);
        }
    }

    function processLink () {
        if (this.className === sAjaxClass) {
            requestPage(this.href);
            return false;
        }
        return true;
    }

    function init () {
        oPageInfo.title = document.title;
        history.replaceState(oPageInfo, oPageInfo.title, oPageInfo.url);
        for (var oLink, nIdx = 0, nLen = document.links.length; nIdx < nLen; document.links[nIdx++].onclick = processLink);
    }

    const

        /* customizable constants */
        sTargetId = "ajax-content", sViewKey = "view_as", sAjaxClass = "ajax-nav",

        /* not customizable constants */
        rSearch = /\?.*$/, rHost = /^[^\?]*\?*&*/, rView = new RegExp("&" + sViewKey + "\\=[^&]*|&*$", "i"), rEndQstMark = /\?$/,
        oLoadingBox = document.createElement("div"), oCover = document.createElement("div"), oLoadingImg = new Image(),
        oPageInfo = {
            title: null,
            url: location.href
        }, oHTTPStatus = /* http://www.iana.org/assignments/http-status-codes/http-status-codes.xml */ {
            100: "Continue",
            101: "Switching Protocols",
            102: "Processing",
            200: "OK",
            201: "Created",
            202: "Accepted",
            203: "Non-Authoritative Information",
            204: "No Content",
            205: "Reset Content",
            206: "Partial Content",
            207: "Multi-Status",
            208: "Already Reported",
            226: "IM Used",
            300: "Multiple Choices",
            301: "Moved Permanently",
            302: "Found",
            303: "See Other",
            304: "Not Modified",
            305: "Use Proxy",
            306: "Reserved",
            307: "Temporary Redirect",
            308: "Permanent Redirect",
            400: "Bad Request",
            401: "Unauthorized",
            402: "Payment Required",
            403: "Forbidden",
            404: "Not Found",
            405: "Method Not Allowed",
            406: "Not Acceptable",
            407: "Proxy Authentication Required",
            408: "Request Timeout",
            409: "Conflict",
            410: "Gone",
            411: "Length Required",
            412: "Precondition Failed",
            413: "Request Entity Too Large",
            414: "Request-URI Too Long",
            415: "Unsupported Media Type",
            416: "Requested Range Not Satisfiable",
            417: "Expectation Failed",
            422: "Unprocessable Entity",
            423: "Locked",
            424: "Failed Dependency",
            425: "Unassigned",
            426: "Upgrade Required",
            427: "Unassigned",
            428: "Precondition Required",
            429: "Too Many Requests",
            430: "Unassigned",
            431: "Request Header Fields Too Large",
            500: "Internal Server Error",
            501: "Not Implemented",
            502: "Bad Gateway",
            503: "Service Unavailable",
            504: "Gateway Timeout",
            505: "HTTP Version Not Supported",
            506: "Variant Also Negotiates (Experimental)",
            507: "Insufficient Storage",
            508: "Loop Detected",
            509: "Unassigned",
            510: "Not Extended",
            511: "Network Authentication Required"
        };

    var

        oReq, bIsLoading = false, bUpdateURL = false;

    oLoadingBox.id = "ajax-loader";
    oCover.onclick = abortReq;
    oLoadingImg.src = "data:image/gif;base64,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";
    oCover.appendChild(oLoadingImg);
    oLoadingBox.appendChild(oCover);

    onpopstate = function (oEvent) {
        bUpdateURL = false;
        oPageInfo.title = oEvent.state.title;
        oPageInfo.url = oEvent.state.url;
        getPage();
    };

    window.addEventListener ? addEventListener("load", init, false) : window.attachEvent ? attachEvent("onload", init) : (onload = init);

    // Public methods

    this.open = requestPage;
    this.stop = abortReq;
    this.rebuildLinks = init;

})();

For more information, please see: Manipulating the browser history (en-US).

See also