appengine_module/components/net.html

<!--
Copyright (C) 2011 Google Inc. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
THE POSSIBILITY OF SUCH DAMAGE.
-->

<script>

var net = net || {};

(function () {

net.json = function(url)
{
    return net.ajax({
        url: url,
        parse: function(xhr) {
            return JSON.parse(xhr.responseText);
        }
    });
};

net.xml = function(url)
{
    return net.ajax({
        url: url,
        parse: function(xhr) {
            return xhr.responseXML;
        }
    });
};

net.ajax = function(options)
{
    return new Promise(function(resolve, reject) {
        var xhr = new XMLHttpRequest();
        var method = options.type || 'GET';
        var async = true;
        xhr.open(method, options.url, async);
        xhr.onload = function() {
            if (xhr.status == 200) {
                if (options.parse)
                    resolve(options.parse(xhr));
                else
                    resolve(xhr.responseText);
            }
            else if (xhr.status != 200)
                reject(Error(xhr.statusText));
        };
        xhr.onerror = function(error) {
            reject(error);
        };
        var data = options.data || null;
        if (data)
            xhr.setRequestHeader("content-type","application/x-www-form-urlencoded");
        xhr.send(data);
    });
};

net.probe = function(url)
{
    return net.ajax({
        url: url,
        type: 'HEAD',
    });
};

net._parseJSONP = function(jsonp)
{
    if (!jsonp)
        return {};

    if (!jsonp.match(/^[^{[]*\(/))
        return JSON.parse(jsonp);

    var startIndex = jsonp.indexOf('(') + 1;
    var endIndex = jsonp.lastIndexOf(')');
    if (startIndex == 0 || endIndex == -1)
        return {};
    return JSON.parse(jsonp.substr(startIndex, endIndex - startIndex));
};

// We use XMLHttpRequest and CORS to fetch JSONP rather than using script tags.
// That's better for security and performance, but we need the server to cooperate
// by setting CORS headers.
net.jsonp = function(url)
{
    return net.ajax({
        url: url,
    }).then(function(jsonp) {
        return net._parseJSONP(jsonp);
    }).catch(function(error) {
        return {};
    });
};

})();

</script>