dojo/request/notify¶
| authors: | Bryan Forbes |
|---|---|
| since: | V1.8 |
Contents
dojo/request/notify is a module that provides an interface for listening for global events emitted by the Request API.
Introduction¶
As part of the Request API, providers will emit events during certain operations. dojo/request/notify is an
interface for listening for these events.
Usage¶
An example of listening for provider events:
require(["dojo/request", "dojo/request/notify"], function(request, notify){
notify("start", function(){
// Do something when the request queue has started
// This event won't fire again until "stop" has fired
});
notify("send", function(response, cancel){
// Do something before a request has been sent
// Calling cancel() will prevent the request from
// being sent
});
notify("load", function(response){
// Do something when a request has succeeded
});
notify("error", function(error){
// Do something when a request has failed
});
notify("done", function(responseOrError){
// Do something whether a request has succeeded or failed
if(responseOrError instanceof Error){
// Do something when a request has failed
}else{
// Do something when a request has succeeded
}
});
notify("stop", function(){
// Do something when all in-flight requests have finished
});
request.get("something.json");
});
dojo/request/notify() takes two arguments:
| Argument | Type | Description |
|---|---|---|
| event | String | The event to be notified of. |
| listener | Function | A function to be called when the event is emitted. |
The events supported are:
| Event | Arguments | Description |
|---|---|---|
| start | None | In-flight requests have started |
| send | Response, Cancel function | Emitted prior to a provider sending data; calling cancel prevents the request from being sent |
| load | Response | A request successfully completed |
| error | Response | A request failed |
| done | Response | A request has finished (regardless of success or failure) |
| stop | None | All in-flight requests have finished |
dojo/request/notify() returns an object with a remove() method. When remove() is called, the listener
will no longer be called when the event it was registered for is emitted.
Examples¶
This example listens to all the events supported and then makes a request to retrieve some JSON and displays the results.
require(["dojo/request/xhr", "dojo/request/notify", "dojo/on", "dojo/dom", "dojo/dom-construct",
"dojo/json", "dojo/domReady!"],
function(xhr, notify, on, dom, domConst, JSON){
notify("start", function(){
domConst.place("<p>start</p>", "output");
});
notify("send", function(response, cancel){
// cancel() can be called to prevent the request from
// being sent
domConst.place("<p>send: <code>" + JSON.stringify(response) + "</code></p>", "output");
});
notify("load", function(response){
domConst.place("<p>load: <code>" + JSON.stringify(response) + "</code></p>", "output");
});
notify("error", function(response){
domConst.place("<p>error: <code>" + JSON.stringify(response) + "</code></p>", "output");
});
notify("done", function(response){
domConst.place("<p>done: <code>" + JSON.stringify(response) + "</code></p>", "output");
});
notify("stop", function(){
domConst.place("<p>stop</p>", "output");
});
on(dom.byId("startButton"), "click", function(){
xhr.get("helloworld.json", {
handleAs: "json"
}).then(function(data){
domConst.place("<p>request data: <code>" + JSON.stringify(data) + "</code></p>", "output");
});
});
});
<h1>Output:</h1>
<div id="output"></div>
<button type="button" id="startButton">Start</button>
See also¶
- dojo/request - The Request API package
- dojo/request/xhr - The default provider for browser platforms
- dojo/request/node - The default provider for the node.js platform
- dojo/request/iframe - A provider that uses IFrame for transport
- dojo/request/script - A provider that expects the response to be embedded in a
<script>tag.