How to Handle Syntax Errors in Node.js ? - GeeksforGeeks (2024)

If there is a syntax error while working with Node.js it occurs when the code you have written violates the rules of the programming language you are using. In the case of Node.js, a syntax error might occur if you have mistyped a keyword, or if you have forgotten to close a parenthesis or curly brace.

Example: Of Syntax Error

const http= require('http');const server= http.createServer(function (req, res){ res.write('Hello World!');}));

Output:

Uncaught SyntaxError: Unexpected token ')'

Approach

To handle a syntax error in Node.js, you can try the following approaches

• Check the error message that appears in the console. This message can provide information on the nature of the error and the location in the code where it occurred.
• Review your code carefully and look for any typos or mistakes. Make sure that you have used proper spelling, punctuation, and special characters.
• Make sure that your code is properly indented. Proper indentation can make it easier to spot missing or misplaced braces or parentheses, which can cause syntax errors.
• To ensure that your code is free of syntax errors, it is important to make sure that you are using the correct syntax for the version of Node.js that you are running. If you are using a newer version of Node.js, some syntax that was previously accepted may no longer be supported, so it is essential to check the documentation for the version you are using.

Third-party tools to Handle Syntax Errors

There are several third-party tools that can help you check for and handle syntax errors in Node.js. Some examples include:

Use a Linter

A linter is a tool that checks your code for syntax errors and other issues. There are various linters available for Node.js, such as ESLint, JSHint, etc. These tools can help you find and fix syntax errors before you run your code.

To use a linter for syntax error checking in Node.js, you will need to install and run the file using JSHint.

Here is an example of how you might do this:-

Choose a linter and install it by running the appropriate command in your terminal/PowerShell.

For example, to install JSHint, you would run:

npm install -g jshint

This will install the linter globally on your system, allowing you to use it from any project.

Run the linter on your code by running the appropriate command in your project directory. For example, to run JSHint on a file named “file.js”, you would run:

jshint file.js

This will check your code for syntax errors and other issues according to the rules specified in your configuration file. If the linter finds any problems, it will display an error message indicating the location and nature of the issue.

Example:

Using Nodemon:

Nodemon is a tool that automatically restarts your Node.js application whenever you make changes to your code. It is typically used during development to make it easier to test and debug your code. Nodemon does not have the ability to check your code for syntax errors on its own, but it can be used in conjunction with a linter to help you find and fix syntax errors in your code.

To use nodemon with a linter for syntax error checking in Node.js, you will need to install both tools and configure them for your project. Here is an example of how you might do this:

Install nodemon and the linter by running the appropriate commands in your terminal. For example, to install nodemon and JSHint, you would run:

npm install -g nodemon jshint

This will install both tools globally on your system, allowing you to use them from any project.

Start nodemon with the linter by running the following command in your project directory:

nodemon --exec "jshint file.js"

This will start nodemon and run the linter on your code whenever you make changes to your code. If the linter finds any syntax errors or other issues, it will display an error message indicating the location and nature of the issue.

Example:

Please go through Explain some Error Handling approaches in the Node.js article to know more about Error Handling approaches.