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Where to write javascript

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WBOYOriginal
2023-05-12 12:13:361057browse

JavaScript is a widely used programming language that can be written in a variety of environments. In this article, we will cover where JavaScript is written and how to use it.

1. JavaScript in the browser
The browser is one of the most common environments where JavaScript is used. Almost all browsers support JavaScript, and they all have JavaScript interpreters built into the browser. You can use JavaScript in your browser to write dynamic web pages, change the style and content of web pages, and communicate with the server.

There are many ways to write JavaScript in the browser. You can use the 3f1c4e4b6b16bbbd69b2ee476dc4f83a tag on the page to call an external JavaScript file, or you can embed JavaScript code in the page. For example, in an HTML file, you can add a simple JavaScript function using the following code: 

<html>
<head>
  <title>My Page</title>
  <script>
    function sayHello(){
      console.log("Hello, world!");
    }
  </script>
</head>
<body>
  <h1>Welcome to my page!</h1>
  <button onclick="sayHello()">Say Hello</button>
</body>
</html>

In this example, we define a function called "sayHello" and add it to the page A button that, when clicked, triggers the function and prints "Hello, world!" to the console. In this code, JavaScript code is embedded in the HTML file.

In addition to embedding JavaScript code in the page, you can also save the JavaScript code to an external file and call them in the page using the 3f1c4e4b6b16bbbd69b2ee476dc4f83a element. For example, in the same HTML folder you can have a file called "script.js" which contains the following code: 

function sayHello(){
  console.log("Hello, world!");
}

Then you can call this function in the HTML file using the following code :

<html>
<head>
  <title>My Page</title>
  <script src="script.js"></script>
</head>
<body>
  <h1>Welcome to my page!</h1>
  <button onclick="sayHello()">Say Hello</button>
</body>
</html>

In this example, we use the 3f1c4e4b6b16bbbd69b2ee476dc4f83a element to call the JavaScript code located in the "script.js" file.

2. JavaScript in Node.js
In addition to writing JavaScript in the browser, you can also write JavaScript in Node.js. Node.js is a server-side JavaScript runtime environment that allows you to write JavaScript code on the server side and communicate with databases, file systems, and other resources.

Writing JavaScript in Node.js is largely the same as in the browser. You can save JavaScript codes to files and then run them using Node.js commands. For example, in a file named "server.js", you can create an HTTP server using the following code: 

const http = require('http');
const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello, world!
');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

In this example, we create an HTTP server named The HTTP server for "server", which will listen for requests on port 3000 of the local host. We then set the response's status code to 200, set the response's content type to "text/plain", and have "Hello, world!" as the body of the response.

3. JavaScript in other environments
In addition to browsers and Node.js, JavaScript can also be written in some other environments. For example, Google Apps Script is part of Google Apps and allows you to write JavaScript code in Google Docs, Sheets, and Slides. There are also desktop apps and mobile app platforms such as Electron and React Native that support JavaScript as well.

Summary
In this article, we introduced ways to write JavaScript in a variety of environments. You can write JavaScript in your browser to dynamically change the content and style of web pages. You can also write JavaScript in Node.js to communicate with databases, file systems, and other resources. Additionally, JavaScript can be used in a number of other environments, such as desktop applications and mobile application platforms. No matter which environment you use, JavaScript is a powerful programming language that can help you build better applications.

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