External Libraries

You can use external front-end libraries and node packages to enhance an app's functionality. This section lists the libraries that you can use and methods to include them in an app.

Front-end Libraries

To use an external library, in the template.html file, specify the library's corresponding reference in the Content Delivery Network (CDN).

Example 1: jQuery
You can use jQuery libraries to add certain UI elements to an app. For example, to add a button in an app’s UI, use the following snippet.

template.html

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<html>
  <head>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script>
  $(document).ready(function(){
    $("button").click(function(){
      alert("This is an alert to quit!")
      });
  });
  </script>
  </head>
  <body>
  <button>Send Warning</button>
  </body>
  </html>
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Example 2: Handlebars
You can use handlebars to build semantic templates. To use handlerbars, include the corresponding library in the app or download the library to the app project directory and provide a reference in the template.html file.

template.html

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<script src="library/handlebars.js"></script>

handlebars.js is the downloaded library file located in the app/library directory.

NPM Packages

You can use npm packages to leverage the back-end functionalities provided by the packages. To use an npm package, specify the package name and version as a dependency in the manifest.json file and include the code corresponding to the package in the server.js file.

Example 1: Request - Helps you to make HTTP calls easily
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var request = require("request");
request("http://www.google.com", function (error, response, body) {
  console.log("error:", error);
  // Print the error if one occurred
  console.log("statusCode:", response && response.statusCode);
  // Print the response status code if a response was received
  console.log("body:", body);
  // Print the HTML for the Google homepage.
});
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"dependencies": {
  "request": "1.8.3"
}
Example 2: Underscore - Contains various utility methods
  • First - Returns the first element of an array.
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    		var _ = require("underscore");
var values = [5, 4, 3, 2, 1];
_.first(values);
/* Returns value 5 */
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    		"dependencies": {
  "underscore": "1.8.3"
}

  • Uniq - Returns all unique values in an array.
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    		var _ = require("underscore");
var values = [1, 2, 1, 4, 1, 3];
_.uniq(values);
/* Returns arrray [1, 2, 4, 3] */
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    		"dependencies": {
  "underscore": "1.8.3"
}