Events & Filters¶
CasperJS provides an event handler very similar to the nodejs’ one; actually it borrows most of its codebase. CasperJS also adds filters, which are basically ways to alter values asynchronously.
Using events is pretty much straightforward if you’re a node developer, or if you worked with any evented system before:
var casper = require('casper').create();
casper.on('resource.received', function(resource) {
casper.echo(resource.url);
});
Emitting you own events¶
Of course you can emit your own events, using the Casper.emit()
method:
var casper = require('casper').create();
// listening to a custom event
casper.on('google.loaded', function() {
this.echo('Google page title is ' + this.getTitle());
});
casper.start('http://google.com/', function() {
// emitting a custom event
this.emit('google.loaded');
});
casper.run();
Removing events¶
You can also remove events. This is particularly useful when running a lot of tests where you might need to add and remove different events for different tests:
var casper = require('casper').create();
// listener function for requested resources
var listener = function(resource, request) {
this.echo(resource.url);
};
// listening to all resources requests
casper.on("resource.requested", listener);
// load the google homepage
casper.start('http://google.com/', function() {
this.echo(this.getTitle());
});
casper.run().then(function() {
// remove the event listener
this.removeListener("resource.requested", listener);
});
Here is an example of how to use this in a casperjs test within the tearDown function.:
var currentRequest;
//Resource listener
function onResourceRequested(requestData, request) {
if (/\/jquery\.min\.js/.test(requestData.url)) {
currentRequest = requestData;
}
}
casper.test.begin('JQuery Test', 1, {
setUp: function() {
// Attach the resource listener
casper.on('resource.requested', onResourceRequested);
},
tearDown: function() {
// Remove the resource listener
casper.removeListener('resource.requested', onResourceRequested);
currentRequest = undefined;
},
test: function(test) {
casper.start('http://casperjs.org/', function() {
test.assert(currentRequest !== undefined, "JQuery Exists");
});
casper.run(function() {
test.done();
});
}
});
Events
reference¶
complete.error
¶
Arguments: error
New in version 1.1.
Emitted when a complete callback has errored.
By default, CasperJS doesn’t listen to this event, you have to declare your own listeners by hand:
casper.on('complete.error', function(err) {
this.die("Complete callback has failed: " + err);
});
downloaded.file
¶
Arguments: targetPath
Emitted when a file has been downloaded by Casper.download(); target
will contain the path to the downloaded file.
downloaded.error
¶
Arguments: url
Emitted when a file has encoutered an error when downloaded by Casper.download(); url
will contain the url of the downloaded file.
error
¶
Arguments: msg, backtrace
New in version 0.6.9.
Emitted when an error hasn’t been explicitly caught within the CasperJS/PhantomJS environment. Do basically what PhantomJS’ onError()
native handler does.
fill
¶
Arguments: selector, vals, submit
Emitted when a form is filled using the Casper.fill()
method.
forward
¶
Arguments: None
Emitted when the embedded browser is asked to go forward a step in its history.
frame.changed
¶
Arguments: name, status
Emitted when the current frame is changed with Casper.withPopup, Casper.switchToFrame() ...
.
http.status.[code]
¶
Arguments: resource
Emitted when any given HTTP reponse is received with the status code specified by [code]
, eg.:
casper.on('http.status.404', function(resource) {
casper.echo(resource.url + ' is 404');
})
load.started
¶
Arguments: None
Emitted when PhantomJS’ WebPage.onLoadStarted
event callback is called.
load.failed
¶
Arguments: Object
Emitted when PhantomJS’ WebPage.onLoadFinished
event callback has been called and failed.
load.finished
¶
Arguments: status
Emitted when PhantomJS’ WebPage.onLoadFinished
event callback is called.
log
¶
Arguments: entry
Emitted when the Casper.log()
method has been called. The entry
parameter is an Object like this:
{
level: "debug",
space: "phantom",
message: "A message",
date: "a javascript Date instance"
}
mouse.down
¶
Arguments: args
Emitted when the mouse presses on something or somewhere with the left button.
mouse.up
¶
Arguments: args
Emitted when the mouse releases the left button over something or somewhere.
open
¶
location, settings
Emitted when an HTTP request is sent. First callback arg is the location, second one is a request settings Object of the form:
{
method: "post",
data: "foo=42&chuck=norris"
}
page.created
¶
Arguments: page
Emitted when PhantomJS’ WebPage
object used by CasperJS has been created.
page.error
¶
Arguments: message, trace
Emitted when retrieved page leaves a Javascript error uncaught:
casper.on("page.error", function(msg, trace) {
this.echo("Error: " + msg, "ERROR");
});
page.initialized
¶
Arguments: WebPage
Emitted when PhantomJS’ WebPage
object used by CasperJS has been initialized.
page.resource.received
¶
Arguments: responseData
Emitted when the HTTP response corresponding to current required url has been received:
casper.on('page.resource.received', function(responseData) {
this.echo(responseData.url);
});
Properties of responseData are:
id
: the number of the requested resourceurl
: the url of the resourcetime
: a Date objectheaders
: the list of headers (list of objects {name:’‘, value:’‘})bodySize
: the size of the received content (may increase during multiple call of the callback)contentType
: the content type of the resourcecontentCharset
: the charset used for the content of the resource (slimerjs only).redirectURL
: if the request has been redirected, this is the redirected urlstage
: “start”, “end” or “” for intermediate chunk of datastatus
: the HTTP response code (200..)statusText
: the HTTP response text for the status (“Ok”…)referrer
: the referer url (slimerjs only)body
: the content, it may change during multiple call for the same request (slimerjs only).httpVersion.major
: the major part of the HTTP protocol version (slimerjs only).httpVersion.minor
: the minor part of the HTTP protocol version (slimerjs only).
page.resource.requested
¶
Arguments: request
Emitted when a new HTTP request is performed to open the required url.
New in version 1.1.
Arguments: requestData, networkRequest
You can also abort requests:
casper.on('page.resource.requested', function(requestData, networkRequest) {
if (requestData.url.indexOf('http://adserver.com') === 0) {
networkRequest.abort();
}
});
Properties of requestData are:
id
: the number of the requested resourcemethod
: the http method (“get”, “post”..)url
: the url of the resourcetime
: a Date objectheaders
: the list of headers (list of objects {name:’‘, value:’‘})postData
: a string containing the body of the request, when method is “post” or “put” (SlimerJS 0.9)
The networkRequest object has two methods:
abort()
: call it to cancel the request. onResourceReceived and onLoadFinished will be called.changeUrl(url)
: abort the current request and do an immediate redirection to the given url.setHeader(key, value, merge)
: allows you to set an header on the HTTP request. If value is null or an empty string, the header will be removed. The merge parameter (only available on SlimerJS), is a boolean: true to merge the given value with an existing value for this header. If false, the old value is replaced by the new one. (Introduced: SlimerJS 0.9)
remote.callback
¶
Arguments: data
Emitted when a remote window.callPhantom(data) call has been performed.
remote.longRunningScript
¶
Arguments: WebPage
Emitted when any remote longRunningScript call has been performed.
You have to call stopJavaScript
method
casper.on('remote.longRunningScript', function stopLongScript(webpage) {
webpage.stopJavaScript();
return true;
});
resource.error
¶
Arguments: resourceError
Emitted when any requested resource fails to load properly. The received resourceError
object has the following properties:
errorCode
: error codeerrorString
: error descriptionurl
: resource urlid
: resource id
resource.received
¶
Arguments: resource
Emitted when any resource has been received.
Arguments: responseData
Emitted when the HTTP response corresponding to current required url has been received:
casper.on('resource.received', function(responseData) {
this.echo(responseData.url);
});
Properties of responseData are:
id
: the number of the requested resourceurl
: the url of the resourcetime
: a Date objectheaders
: the list of headers (list of objects {name:’‘, value:’‘})bodySize
: the size of the received content (may increase during multiple call of the callback)contentType
: the content type of the resourcecontentCharset
: the charset used for the content of the resource (slimerjs only).redirectURL
: if the request has been redirected, this is the redirected urlstage
: “start”, “end” or “” for intermediate chunk of datastatus
: the HTTP response code (200..)statusText
: the HTTP response text for the status (“Ok”…)referrer
: the referer url (slimerjs only)body
: the content, it may change during multiple call for the same request (slimerjs only).httpVersion.major
: the major part of the HTTP protocol version (slimerjs only).httpVersion.minor
: the minor part of the HTTP protocol version (slimerjs only).
resource.requested
¶
Arguments: requestData, networkRequest
You can also abort or change requests and alse update Headers
casper.on('resource.requested', function(requestData, networkRequest) {
if (requestData.url.indexOf('http://adserver.com') === 0) {
networkRequest.abort();
}
});
Properties of requestData are:
id
: the number of the requested resourcemethod
: the http method (“get”, “post”..)url
: the url of the resourcetime
: a Date objectheaders
: the list of headers (list of objects {name:’‘, value:’‘})postData
: a string containing the body of the request, when method is “post” or “put” (SlimerJS 0.9)
The networkRequest object has two methods:
abort()
: call it to cancel the request. onResourceReceived and onLoadFinished will be called.changeUrl(url)
: abort the current request and do an immediate redirection to the given url.setHeader(key, value, merge)
: allows you to set an header on the HTTP request. If value is null or an empty string, the header will be removed. The merge parameter (only available on SlimerJS), is a boolean: true to merge the given value with an existing value for this header. If false, the old value is replaced by the new one. (Introduced: SlimerJS 0.9)
resource.timeout
¶
Arguments: request
Emitted when the execution time of any resource has exceeded the value of settings.resourceTimeout.
you can configure timeout with settings.resourceTimeout
parameter.
Properties of responseData are:
id
: the number of the requested resourceurl
: the url of the resourceerrorCode
: an error code: 408errorString
: the error message.time
: a Date objectheaders
: the list of headers (list of objects {name:’‘, value:’‘})method
: the http method (“get”, “post”..)
run.complete
¶
Arguments: None
Emitted when the whole series of steps in the stack have been executed.
step.bypassed
¶
Arguments: step, step
Emitted when a new navigation step has been reached by bypass (destination, origin).
step.error
¶
Arguments: error
New in version 1.1.
Emitted when a step function has errored.
By default, CasperJS doesn’t listen to this event, you have to declare your own listeners by hand:
casper.on('step.error', function(err) {
this.die("Step has failed: " + err);
});
timeout
¶
Arguments: None
Emitted when the execution time of the script has reached the Casper.options.timeout
value.
waitFor.timeout
¶
Arguments: [timeout, details]
Emitted when the execution time of a Casper.wait*()
operation has exceeded the value of timeout
.
details
is a property bag describing what was being waited on. For example, if waitForSelector
timed out, details
will have a selector
string property that was the selector that did not show up in time.
Filters
Reference¶
Filters allow you to alter some values asynchronously. Sounds obscure? Let’s take a simple example and imagine you would like to alter every single url opened by CasperJS to append a foo=42
query string parameter:
var casper = require('casper').create();
casper.setFilter('open.location', function(location) {
return /\?+/.test(location) ? location += "&foo=42" : location += "?foo=42";
});
There you have it, every single requested url will have this appended. Let me bet you’ll find far more interesting use cases than my silly one ;)
Every filter methods called emit an identical event. For instance, “page.confirm” filter sends “page.confirm” event.
Here’a the list of all available filters with their expected return value:
Filters reference
capture.target_filename
¶
Arguments: args
Return type: String
Allows to alter the value of the filename where a screen capture should be stored.
echo.message
¶
Arguments: message
Return type: String
Allows to alter every message written onto stdout.
fileDownload
¶
Arguments: url, Object [filename,size,contentType]
Return type: String
Allows to alter the path for the file that must be downloaded.
open.location
¶
Arguments: args
Return type: String
Allows to alter every url before it being opened.
page.confirm
¶
Arguments: message
Return type: Boolean
New in version 1.0.
Allows to react on a javascript confirm()
call:
casper.setFilter("page.confirm", function(msg) {
return msg === "Do you like vbscript?" ? false : true;
});
page.filePicker
¶
Arguments: oldFile
Return type: String
New in version 1.4.
Allows to react on a webpage.onFilePicker call:
casper.setFilter("page.filePicker", function(oldFile) {
if (system.os.name === 'windows') {
return 'C:\\Windows\\System32\\drivers\\etc\\hosts';
}
return '/etc/hosts';
});
page.prompt
¶
Arguments: message, value
Return type: String
New in version 1.0.
Allows to react on a javascript prompt()
call:
casper.setFilter("page.prompt", function(msg, value) {
if (msg === "What's your name?") {
return "Chuck";
}
});