- \n
- Declaring variables<\/li>\n
- Maintaining the retrieving values<\/li>\n
- Defining and invoking functions<\/li>\n
- Defining classes<\/li>\n
- Load and use external modules<\/li>\n
- Define event handlers<\/li>\n
- And much more \u2026.<\/li>\n<\/ul>\n
[ulp id=’tCIwOngQUb3zSUuF’]<\/p>\n
1.1 Advantages of JavaScript Language<\/h3>\n
The pros of using the JavaScript scripting language are:<\/p>\n
- \n
- JavaScript is easy to learn<\/li>\n
- It executes on client’s browser, so eliminates the server-side processing and be executed on any OS<\/li>\n
- JavaScript can be used with any type of web page e.g. PHP, ASP.NET, Perl etc<\/li>\n
- Web-page performance increases due to client-side execution<\/li>\n
- JavaScript code can be minified to decrease the loading time from the server<\/li>\n
- Many JavaScript-based application frameworks are available in the market to create Single page web applications e.g. AngularJS, ReactJS etc.<\/li>\n<\/ul>\n
1.2 Disadvantages of JavaScript Language<\/h3>\n
The cons of using the JavaScript scripting language are:<\/p>\n
- \n
- No support for networking applications<\/li>\n
- Does not have any multi-threading or multi-processing capabilities<\/li>\n
- Does not allow the file reading and writing capabilities<\/li>\n<\/ul>\n
1.3 Fetch API in JavaScript<\/h2>\n
- \n
- In javascript, Fetch<\/strong> API is an interface to fetch the resources from the server<\/li>\n
- Fetch API uses promises<\/em> to support the asynchronous programming by making the code look synchronous and avoiding problems associated with callbacks<\/li>\n
- The
fetch()<\/code> method allows the developers to make the network requests similar to XMLHttpRequest (XHR)<\/li>\n- The
fetch()<\/code> method is defined on a window<\/em> object, which developers use to perform requests and sent it to a server<\/li>\n- The
fetch()<\/code> method accepts only resource url<\/em> as a mandatory argument<\/li>\n<\/ul>\n2. JavaScript Fetch Example<\/h2>\n
Here is a systematic guide for implementing this tutorial using the JavaScript language.<\/p>\n
2.1 Tools Used<\/h3>\n
We are using Eclipse Kepler SR2, JDK 8 and Maven. Having said that, we have tested the code against JDK 1.7 and it works well.<\/p>\n
2.2 Project Structure<\/h3>\n
Firstly, let us review the final project structure if you are confused about where you should create the corresponding files or folder later!<\/p>\n
![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/structure-img-1-1.jpg\")
<\/a>Fig. 1: Application Project Structure<\/figcaption><\/figure>\n 2.3 Project Creation<\/h3>\n
This section will show on how to create a Java-based Maven project with Eclipse. In Eclipse Ide, go to
File -> New -> Maven Project<\/code>.<\/p>\n![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/js_fetch_project_guide_1.jpg\")
<\/a>Fig. 2: Create a Maven Project<\/figcaption><\/figure>\n In the New Maven Project window, it will ask you to select the project location. By default, ‘Use default workspace location’ will be selected. Just click on the next button to proceed.<\/p>\n
![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/js_fetch_project_guide_2.jpg\")
<\/a>Fig. 3: Project Details<\/figcaption><\/figure>\n Select the ‘Maven Web App’ Archetype from the list of options and click next.<\/p>\n
![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/js_fetch_project_guide_3.jpg\")
<\/a>Fig. 4: Archetype Selection<\/figcaption><\/figure>\n It will ask you to ‘Enter the group and the artifact id for the project’. We will input the details as shown in the below image. The version number will be by default:
0.0.1-SNAPSHOT<\/code>.<\/p>\n![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/js_fetch_project_guide_4.jpg\")
<\/a>Fig. 5: Archetype Parameters<\/figcaption><\/figure>\n Click on Finish and the creation of a maven project is completed. If you see, it has downloaded the maven dependencies and a
pom.xml<\/code> file will be created. It will have the following code:<\/p>\npom.xml<\/em><\/span><\/p>\n
<project xmlns=\"http:\/\/maven.apache.org\/POM\/4.0.0\" xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\" xsi:schemaLocation=\"http:\/\/maven.apache.org\/POM\/4.0.0 http:\/\/maven.apache.org\/xsd\/maven-4.0.0.xsd\">\r\n\t<modelVersion>4.0.0<\/modelVersion>\r\n\t<groupId>com.javascript<\/groupId>\r\n\t<artifactId>JavascriptFetchApi<\/artifactId>\r\n\t<version>0.0.1-SNAPSHOT<\/version>\r\n\t<packaging>war<\/packaging>\r\n<\/project>\r\n<\/pre>\n
3. Application Building<\/h2>\n
Let us create an application to understand the basic building blocks of this tutorial.<\/p>\n
3.1 Define the HTML<\/h3>\n
Let us write a simple index page in the
JavascriptFetchApi\/src\/main\/webapp\/<\/code> folder. Add the following code to it:<\/p>\nindex.jsp<\/em><\/span><\/p>\n
<!-- Javascript fetch() method tutorial -->\r\n<h6 class=\"text-info\">Click the button to fetch the data from the server.<\/h6>\r\n<div>\u00a0<\/div>\r\n\r\n<button id=\"btn_submit\" type=\"button\" class=\"btn btn-success\" onclick=\"fetchProduct();\">Fetch<\/button>\r\n<div>\u00a0<\/div>\r\n\r\n<ul id=\"product\"><\/ul>\r\n<\/pre>\n
3.2 Define the JavaScript function<\/h3>\n
Let us write a simple javascript function that shows the fetch interface<\/span> implementation in the javascript language. Add the following code to it:<\/p>\n
JavaScript function<\/em><\/span><\/p>\n
var ul = document.getElementById(\"product\");\r\nconst url = \"<-- Enter url to fetch the resources from the server -->\";\r\n\r\n\/\/ Function to fetch the data from the server.\r\nfunction fetchProduct() {\r\n\tfetch(url).then((res) => res.json()).then((json) => {\r\n\t\tconsole.log(json);\r\n\t\tfor(var i=0; i < json.items.length; i++) {\r\n\t\t\tvar li = document.createElement(\"li\");\r\n\t\t\tli.appendChild(document.createTextNode(json.items[i].name));\r\n\t\t\tul.appendChild(li);\r\n\t\t}\r\n\t});\r\n}\r\n<\/pre>\n3.3 First application<\/h3>\n
Complete the above steps and save the file. Let us see the sample code snippet.<\/p>\n
index.jsp<\/em><\/span><\/p>\n
<!DOCTYPE html>\r\n<html lang=\"en\">\r\n\r\n<head>\r\n <title>Index page<\/title>\r\n <meta http-equiv=\"Content-Type\" content=\"text\/html; charset=ISO-8859-1\">\r\n <link rel=\"stylesheet\" href=\"https:\/\/stackpath.bootstrapcdn.com\/bootstrap\/4.1.3\/css\/bootstrap.min.css\">\r\n<\/head>\r\n\r\n<body>\r\n <div class=\"container\">\r\n <h2 align=\"center\" class=\"text-danger\">Fetch API in JavaScript<\/h2>\r\n <hr \/>\r\n\r\n <!-- Javascript fetch() method tutorial -->\r\n\t\t<h6 class=\"text-info\">Click the button to fetch the data from the server.<\/h6>\r\n\t\t<div>\u00a0<\/div>\r\n\t\t\r\n\t\t<button id=\"btn_submit\" type=\"button\" class=\"btn btn-success\" onclick=\"fetchProduct();\">Fetch<\/button>\r\n\t\t<div>\u00a0<\/div>\r\n\t\t\r\n\t\t<ul id=\"product\"><\/ul>\r\n <\/div>\r\n <script>\r\n\t\tvar ul = document.getElementById(\"product\");\r\n\t\tconst url = \"<-- Enter url to fetch the resources from the server -->\";\r\n\t\t\r\n\t\t\/\/ Function to fetch the data from the server.\r\n\t\tfunction fetchProduct() {\r\n\t\t\tfetch(url).then((res) => res.json()).then((json) => {\r\n\t\t\t\tconsole.log(json);\r\n\t\t\t\tfor(var i=0; i < json.items.length; i++) {\r\n\t\t\t\t\tvar li = document.createElement(\"li\");\r\nli.appendChild(document.createTextNode(json.items[i].name));\r\n\t\t\t\t\tul.appendChild(li);\r\n\t\t\t\t}\r\n\t\t\t});\r\n\t\t}\r\n <\/script>\r\n<\/body>\r\n\r\n<\/html>\r\n<\/pre>\n4. Run the Application<\/h2>\n
As we are ready for all the changes, let us compile the project and deploy the application on the Tomcat7 server. To deploy the application on Tomat7, right-click on the project and navigate to
Run as -> Run on Server<\/code>.<\/p>\n![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/deploy-img1-2.jpg\")
<\/a>Fig. 6: How to Deploy Application on Tomcat<\/figcaption><\/figure>\n Tomcat will deploy the application in its web-apps folder and shall start its execution to deploy the project so that we can go ahead and test it in the browser.<\/p>\n
5. Project Demo<\/h2>\n
Open your favorite browser and hit the following URL to display the application\u2019s index page as shown in Fig. 7.<\/p>\n
http:\/\/localhost:8082\/JavascriptFetchApi\/<\/pre>\n
Server name (localhost) and port (8082) may vary as per your Tomcat configuration.<\/p>\n
![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/demo-img1-4.jpg\")
<\/a>Fig. 7: Index page<\/figcaption><\/figure>\n Developers can click the Fetch<\/em> button to fetch the data from the server as shown in fig. 8.<\/p>\n
![\"JavaScript](\"http:\/\/www.webcodegeeks.com\/wp-content\/uploads\/2018\/11\/demo-img2-1.jpg\")
<\/a>Fig. 8: Fetch API in JavaScript<\/figcaption><\/figure>\n That is all for this tutorial and I hope the article served you whatever you were looking for. Happy Learning and do not forget to share!<\/p>\n
6. Conclusion<\/h2>\n
In this section, developers learned how to create a simple application with the JavaScript language. Developers can download the sample application as an Eclipse project in the Downloads<\/a> section.<\/p>\n
<\/a>7. Download the Eclipse Project<\/h2>\n
This was an example of JavaScript Fetch<\/em> example for the beginners.<\/p>\n
- Fetch API uses promises<\/em> to support the asynchronous programming by making the code look synchronous and avoiding problems associated with callbacks<\/li>\n
- In javascript, Fetch<\/strong> API is an interface to fetch the resources from the server<\/li>\n