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| | <metadesc>Communicate over USB with sensors, controllers and relays with Phidgets! Our Visual Basic .NET library supports Windows using Visual Studio or Mono.</metadesc> |
| [[Category:Language]] | | [[Category:Language]] |
| __TOC__
| | __NOTOC__ |
| | We provide support for the JavaScript language for both browsers and node.js. We also provide instructions on how to get your project started in a number of common development environments. Select your operating system and preferred development environment below, and follow the instructions to get your project running with Phidgets. |
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| == Quick Downloads ==
| | General information of how to use Phidgets with JavaScript can be found in the '''Write Code''' section of each development environment page. This information is consistent across all pages. |
| === Documentation ===
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| *{{Phidget22API}} (Select JavaScript from drop-down menu)
| | ==Setup Guide== |
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| === Example Code === | | <div class="phd-deck-sequence"> |
| | {{PT3_JS_CHOOSE}}{{PT3_JS_ANY_BROWSER}}{{PT3_JS_ANY_NODE}} |
| | </div> |
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| *{{SampleCode|JavaScript|JavaScript Examples (Node.js)}}
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| *[{{SERVER}}/downloads/phidget22/tools/any/Phidget22JavaScriptControlPanel.zip Javascript Examples (HTML)]
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| === Libraries === | | == Quick Downloads == |
| | If you already know what you're doing and just need the files, you can find them all below. |
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| *[{{SERVER}}/downloads/phidget22/libraries/any/Phidget22JavaScript.zip JavaScript Library Download]
| | === Documentation === |
| {{AllQuickDownloads}}
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| == Getting Started with JavaScript ==
| | *{{Phidget22API}} (Select JavaScript from drop-down menu) |
| Welcome to using Phidgets with JavaScript! By using JavaScript, you will have access to the complete {{Phidget22API}}, including events. We also provide example code in JavaScript for all Phidget devices.
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| If you are developing for Windows, keep reading. Otherwise, select your operating system to jump ahead:
| | === Libraries === |
| *[[#macOS | macOS]]
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| *[[#Linux | Linux]]
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| == Windows ==
| | *'''Browser''': [https://cdn.phidgets.com/downloads/phidget22/libraries/any/Phidget22JavaScript.zip JavaScript Library Download] |
| {{Windows_Languages}}
| | *'''Node.js''': npm install phidget22 |
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| ===Browser=== | | === Example Code === |
| ====Use Our Examples====
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| One of the best ways to start programming with Phidgets is to use our example code as a guide. Our browser examples are graphical and are installed with the Phidget libraries. In order to check them out, first open the Phidget Control Panel and navigate to the Network Server tab:
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| [[File:Windows_networkserver.PNG|link=|center]]
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| | *[{{SERVER}}?view=code_samples&lang=JavaScript&os=Nodejs JavaScript Examples (Node.js)] |
| | *[{{SERVER}}?view=code_samples&lang=JavaScript&os=Browser JavaScript Examples (Browser)] |
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| Next, make sure the Webserver is enabled (''Enabled'' checkbox in ''Webserver'' section), and start the Phidget Network Server by clicking on the ''Start'' button at the bottom of the window. Click on the hyperlink (or navigate to http://localhost:8989) as shown in the image below:
| | === Tools === |
| [[File:Javascript_windows_localhost.png|link=|center]]
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| | *[https://cdn.phidgets.com/downloads/phidget22/tools/any/Phidget22JavaScriptControlPanel.zip JavaScript Control Panel Source] |
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| You will now see a program that mimics the Phidget Control Panel (and was written entirely with JavaScript/HTML). It will show all the Phidgets attached to your machine. By double-clicking on the Phidgets, and example will launch:
| | === OS Libraries === |
| [[File:Javascript_windows_controlpanel.png|link=|center]]
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| | | {{AllQuickDownloads}} |
| To view the source code, navigate to the following location:
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| *C:/Program Files/Phidgets/Phidget22/html
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| [[File:Javascript_windows_filelocation.png|link=|center]]
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| Here you can view the code that was written to create the main webpage as well as all of the examples.
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| ====Write Your Own Code====
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| Let's start by writing a simple HTML page that makes a dynamic list of attached Phidgets visible to the user.
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| We will be using the JavaScript library [https://jquery.com/download/ jQuery] in these examples. jQuery is not required in order to use Phidgets, however, it will make it easier for us to access elements on an HTML page.
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| To start, create a new folder that looks like this:
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| [[File:Javascript_windows_folderlibraries.png|link=|center]]
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| As stated above, you must download the jQuery library. The rest of the libraries are installed with the Phidget libraries and can be found at the following location:
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| *C:/Program Files/Phidgets/Phidget22/html
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| Next, create a file called ''index.html'' and copy the following code into it (Note: if you have newer JavaScript libraries, modify the code below to match your version numbers):
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| <syntaxhighlight lang=javascript>
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| <!DOCTYPE html>
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| <html>
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| <head>
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| <title>Javascript Test Program</title>
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| <script src="jquery-3.2.1.min.js"></script>
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| <script src="sha256.js"></script>
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| <script src="jphidgets22.1.0.0.min.js"></script>
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| <script>
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| $(document).ready(function () {
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| var conn = new jPhidgets.Connection('ws://' + window.location.host + '/phidgets', { name: window.location.host });
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| conn.connect().then(function () {
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| console.log('connected');
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| }).catch(function (err) {
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| alert('failed to connect to server:' + err);
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| });;
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| conn.onattach = function(dev) {
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| $('#list').append(new Option(dev.name,dev.phid));
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| }
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| conn.ondetach = function(dev) {
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| $("#list option[value='" + dev.phid + "']").remove();
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| }
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| });
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| </script>
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| </head>
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| <body>
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| <label> Attached Phidgets: </label>
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| <div>
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| <select multiple id="list" style="width: 500px;"></select>
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| </div>
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| </body>
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| </html>
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| </syntaxhighlight>
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| After copying the code above into your ''index.html'' file, your folder should look like this:
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| [[File:Javascript windows folder.png|link=|center]]
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| Next, open the Network Server tab in the Phidget Control Panel and modify the Webserver ''Docroot'' to your folders location:
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| [[File:Javascript_windows_docrootchange.png|link=|center]]
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| Finally, click on the hyperlink (or navigate to http://localhost:8989) to see the example:
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| [[File:Javascript_windows_example.png|link=|center]]
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| Open the developer console to get a better idea what is going on:
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| [[File:Javascript_windows_devconsole.png|link=|center]]
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| For information about the Node.js example, keep reading. Otherwise, skip ahead to the [[#Edit the Examples | edit the examples]] section located below.
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| ===Node.js===
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| node.js is a Javascript runtime that will allow us to run Javascript code via the Windows command prompt. Download the latest version of node.js [https://nodejs.org/ here]. The installer will also set the class path and install '''npm''' (the node.js package manager), both of which are necessary for the next steps. Once it's been installed, open up a command prompt by searching for "cmd" in the start menu.
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| You can download our Javascript examples [[#Quick Downloads|here]].
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| In the command prompt, navigate to the folder that contains the Phidgets Javascript examples. There, type the following command:
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| {{Code|npm update}}
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| This will cause the package manager to look at {{Code|package.json}} and update the Phidgets libraries.
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| ====Use Our Examples====
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| To run the examples, go to {{Code|C:\Program Files\Phidgets\Phidget22\}} and run {{Code|NetworkServer.exe}}. A window like the one below should open:
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| [[image:js_networkservice.jpg|link=]]
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| In the other command prompt window, navigate to the folder that contains the Phidgets Javascript examples and type
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| {{Code|node <example> <address>}}
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| where {{Code|<example>}} is the filename of the example you want to run (i.e. DigitalInput.js) and {{Code|<address>}} is the address of the Phidget server. In our case, it will be "localhost" because we're hosting it on the same computer:
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| {{Code|node DigitalInput localhost}}
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| This should result in a simple text-based example to be launched:
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| [[image:js_nodeexample.jpg|link=]]
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| ====Write Your Own Code====
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| After testing with our node.js examples, it will be easy for you to write your own programs. Open up one of the examples and edit the {{Code|runExample()}} function to suit your needs:
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| # Change {{Code|jPhidget22.VoltageInput}} to the object you want to open.
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| # Set new handlers for this channel (for example, {{Code|ch.onIlluminanceChange}} if you're using a light sensor).
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| # Set new parameters to open a specific channel (for example, {{Code|ch.setDeviceSerialNumber()}} or {{Code|ch.setIsHubPort()}}).
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| # You can open multiple channels by declaring different variables for each one and repeating the same process of assigning handlers and calling {{Code|open()}} on the channel.
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| # Edit the contents of the event handlers to do different things with the data. Instead of printing the data to console, you could log it to a .csv file, or perform custom processing on the data (i.e. rolling average).
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| When you're done writing your program, you'll be able to run it in the same way as described in the previous section.
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| == OS X ==
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| === Browser Example (Visual Studio Code) ===
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| === node.js ===
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| == Linux ==
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| === Browser Example ===
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| Download our Javascript libraries [[#Quick Downloads|here]] and follow the instructions in the README to get in-browser Javascript running.
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| === node.js ===
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| node.js is a Javascript runtime that will allow us to run Javascript code via the terminal. Download the latest version of node.js [https://nodejs.org/ here]. The installer will also set the class path and install '''npm''' (the node.js package manager), both of which are necessary for the next steps.
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| Download our Javascript examples [[#Quick Downloads|here]].
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| In the terminal, navigate to the folder that contains the Phidgets Javascript examples. There, type the following command:
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| {{Code|npm update}}
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| This will cause the package manager to look at {{Code|package.json}} and update the Phidgets libraries.
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| Follow the README in the Javascript libraries to get the Phidget network server running.
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| In the terminal, navigate to the folder that contains the Phidgets Javascript examples and type
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| {{Code|node <example> <address>}}
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| where {{Code|<example>}} is the filename of the example you want to run (i.e. DigitalInput.js) and {{Code|<address>}} is the address of the Phidget server. In our case, it will be "localhost" because we're hosting it on the same computer:
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| {{Code|node DigitalInput localhost}}
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| This should result in a simple text-based example to be launched inside the terminal.
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| == Edit the Examples ==
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| By following the instructions for your operating system and compiler above, you probably now have a working example and want to understand it better so you can change it to do what you want. This teaching section has resources for you to learn from the examples and write your own.
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| Your main reference for writing Javascript code will be the {{Phidget22API}} Manual. The following code snippets will also provide a quick reference on how to do specific tasks in Javascript.
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| === Code Snippets ===
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| ==== Step One: Connect====
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| In Javascript, you must first connect to the Phidget server using the {{Code|Connection}} object.
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| <syntaxhighlight lang=javascript>
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| function main() {
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| ...
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| var conn = new jPhidget22.Connection(url, { name: n, passwd: p });
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| conn.connect()
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| .then(runCode);
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| }
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| </syntaxhighlight>
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| Where {{Code|url}}, {{Code|n}}, and {{Code|p}} are variables defined elsewhere in the program. If the connection is successful, we call another function that contains the rest of our code.
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| ==== Step Two: Create and Open====
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| After connecting, the {{Code|Open()}} function opens the software object, and once it has successfully opened we can interact with it and start receiving data from it. We can also set up event handlers just before opening.
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| For example, if we were using an Digital Input as our device, it would look like this:
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| <syntaxhighlight lang=javascript>
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| function runCode() {
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| var ch = new jPhidget22.DigitalInput();
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| ch.onAttach = digitalInput_attach;
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| ch.onStateChange = digitalInput_change;
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| ch.open().then(function() {
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| // code to execute after open succeeds
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| }).catch(function (err) {
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| // code to execute if open fails
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| });
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| }
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| </syntaxhighlight>
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| Once the object successfully opens, you can access it and you will start to get events from it. We can define the event handler functions :
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| <syntaxhighlight lang=javascript>
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| function digitalInput_attach(ch) {
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| console.log(ch + ' attached');
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| }
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| function digitalInput_change(state) {
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| console.log('state changed:' + state);
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| }
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| </syntaxhighlight>
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| Now that they've been registered in the {{Code|runCode()}} function and the device has been opened, these event handlers will be able to trigger. The first one triggers when the DigitalInput channel attaches, and the second one will trigger whenever the state of the attached DigitalInput changes.
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| ==== Step Three: Do Things with the Phidget ====
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| Some values can be directly read and set on the Phidget. These functions can be used inside a polling loop as an alternative to event driven programming. The lines inside the loop would be something like this, after which you could do something with the value:
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| <syntaxhighlight lang=javascript>
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| var di_state = ch.getState(); // get the state of the digital input
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| ch.setState(1); // set the state of the digital input
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| </syntaxhighlight>
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| ==== Step Four: Close ====
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| At the end of your program (or at least, at the end of the part that uses the Phidget), it is advisable to close your device. This ensures that the Phidget will be available to other programs that want to use it, since a channel can only be in use by one program at a time unless it's opened remotely. It's not necessary to delete the object after closing in Javascript.
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| <syntaxhighlight lang=javascript>
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| ch.close();
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|
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| </syntaxhighlight>
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| == Further Reading ==
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| [[Phidget Programming Basics]] - Here you can find the basic concepts to help you get started with making your own programs that use Phidgets.
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| [[Data Interval/Change Trigger]] - Learn about these two properties that control how much data comes in from your sensors.
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| [[Using Multiple Phidgets]] - It can be difficult to figure out how to use more than one Phidget in your program. This page will guide you through the steps.
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| [[Polling vs. Events]] - Your program can gather data in either a polling-driven or event-driven manner. Learn the difference to determine which is best for your application.
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| [[Logging, Exceptions, and Errors]] - Learn about all the tools you can use to debug your program.
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| [[Phidget Network Server]] - Phidgets can be controlled and communicated with over your network- either wirelessly or over ethernet.
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