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phab/webroot/rsrc/js/javelin/lib/Resource.js
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Resource.js
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/**
* @provides javelin-resource
* @requires javelin-magical-init
* javelin-stratcom
* javelin-util
* javelin-uri
*
* @javelin
*/
JX.install('Resource', {
statics: {
_loading: {},
_loaded: {},
_links: [],
_callbacks: [],
/**
* Loads one or many static resources (JavaScript or CSS) and executes a
* callback once these resources have finished loading.
*
* @param string|array static resource or list of resources to be loaded
* @param function callback when resources have finished loading
*/
load: function(list, callback) {
var resources = {},
uri, resource, path, type;
list = JX.$AX(list);
// In the event there are no resources to wait on, call the callback and
// exit. NOTE: it's better to do this check outside this function and not
// call through JX.Resource, but it's not always easy/possible to do so
if (!list.length) {
setTimeout(callback, 0);
return;
}
for (var ii = 0; ii < list.length; ii++) {
uri = new JX.URI(list[ii]);
resource = uri.toString();
path = uri.getPath();
resources[resource] = true;
if (JX.Resource._loaded[resource]) {
setTimeout(JX.bind(JX.Resource, JX.Resource._complete, resource), 0);
} else if (!JX.Resource._loading[resource]) {
JX.Resource._loading[resource] = true;
if (path.indexOf('.css') == path.length - 4) {
JX.Resource._loadCSS(resource);
} else {
JX.Resource._loadJS(resource);
}
}
}
JX.Resource._callbacks.push({
resources: resources,
callback: callback
});
},
_loadJS: function(uri) {
var script = document.createElement('script');
var load_callback = function() {
JX.Resource._complete(uri);
};
var error_callback = function() {
JX.$E('Resource: JS file download failure: ' + uri);
};
JX.copy(script, {
type: 'text/javascript',
src: uri
});
script.onload = load_callback;
script.onerror = error_callback;
script.onreadystatechange = function() {
var state = this.readyState;
if (state == 'complete' || state == 'loaded') {
load_callback();
}
};
document.getElementsByTagName('head')[0].appendChild(script);
},
_loadCSS: function(uri) {
var link = JX.copy(document.createElement('link'), {
type: 'text/css',
rel: 'stylesheet',
href: uri,
'data-href': uri // don't trust href
});
document.getElementsByTagName('head')[0].appendChild(link);
JX.Resource._links.push(link);
if (!JX.Resource._timer) {
JX.Resource._timer = setInterval(JX.Resource._poll, 20);
}
},
_poll: function() {
var sheets = document.styleSheets,
ii = sheets.length,
links = JX.Resource._links;
// Cross Origin CSS loading
// http://yearofmoo.com/2011/03/cross-browser-stylesheet-preloading/
while (ii--) {
var link = sheets[ii],
owner = link.ownerNode || link.owningElement,
jj = links.length;
if (owner) {
while (jj--) {
if (owner == links[jj]) {
JX.Resource._complete(links[jj]['data-href']);
links.splice(jj, 1);
}
}
}
}
if (!links.length) {
clearInterval(JX.Resource._timer);
JX.Resource._timer = null;
}
},
_complete: function(uri) {
var list = JX.Resource._callbacks,
current, ii;
delete JX.Resource._loading[uri];
JX.Resource._loaded[uri] = true;
for (ii = 0; ii < list.length; ii++) {
current = list[ii];
delete current.resources[uri];
if (!JX.Resource._hasResources(current.resources)) {
current.callback();
list.splice(ii--, 1);
}
}
},
_hasResources: function(resources) {
for (var hasResources in resources) {
return true;
}
return false;
}
},
initialize: function() {
var list = JX.$A(document.getElementsByTagName('link')),
ii = list.length,
node;
while ((node = list[--ii])) {
if (node.type == 'text/css' && node.href) {
JX.Resource._loaded[(new JX.URI(node.href)).toString()] = true;
}
}
list = JX.$A(document.getElementsByTagName('script'));
ii = list.length;
while ((node = list[--ii])) {
if (node.type == 'text/javascript' && node.src) {
JX.Resource._loaded[(new JX.URI(node.src)).toString()] = true;
}
}
}
});
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