Node.js - Console

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In Node.JS, the console module is used to provide the simple way to output messages to standard output and standard error. It is widely used for debugging, logging and monitoring applications.

Unlike the traditional browser-based JavaScript, where the console.log() is primarily used for debugging, the Node.js console offers a variety of additional methods personalized for server-side logging and monitoring. Let's dive into the tutorial to understand more about the Node.js console.

Why to Use Console in Node.js

The console module in the Node.js is an essential tool for users providing a simple yet effective way to output messages, debug applications. The console in Node.js allows the users to:

• Debugging − It helps in tracking errors and debugging code efficiently.
• Logging − It is useful for recording events, warnings, and errors.
• Performance Monitoring − It helps in analysing the execution time and resource usage.
• Development & Testing − It simplifies code testing by providing immediate feedback.

Using the Console Module

The Console Module in Node.js is a built-in feature that allows the user to log messages, debug applications. It does not require any external installation, making it easily accessible.

However, for the production environments, it is advisable to use the advanced logging tools like Winston or Bunyan to ensure the structured and determined logging.

Basic Console Methods

The console module in Node.js offers a several methods that helps the user with debugging and logging. These methods allows you to print messages , displays the warnings.

Using the right console methods can improve the efficiency of the development process and improve code readability. Below are some of the most commonly used console methods in Node.js.

The console.log() Method

The console.log() method in Node.js is used to output messages to the console. It is one of the most commonly used methods for debugging and logging information.

Example

console.log("WELCOME");

Output

WELCOME

The console.error() Method

The console.error() method in Node.js is used to output the error messages to the standard error stream instead of the standard output. It is particularly useful for logging errors separately from the application messages.

Example

console.error("An unexpected error occurred!");

Output

An unexpected error occurred!

The console.warn() Method

The console.warn() method is used to output the warning messages, that are typically used for non-critical issues that requires the attention.

Warnings indicates the potential problems in the code that does not stop the execution but should be reviewed and addressed to prevent further errors. It is used to highlight the deprecated features, incorrect configuration.

Example

console.warn("It is warning.!, Please check the Application.");

Output

It is warning.!, Please check the Application.

The console.info() Method

The console.info() method in Node.js is similar to the console.log(), But is often used to log information messages that provides the insights into the applications state.

It is commonly used for non-critical messages, such as status updates, successful operations or general information, which can be useful for debugging or monitoring.

Example

console.info("It is running on port 1212");

Output

It is running on port 1212

Advanced Console Methods

The advanced console methods provides the powerful tools for structured logging and debugging. These methods go beyond the simple logging and allows the user to format outputs, measure the execution times, organize the log messages into groups and visualize tabular data.

These advanced methods are especially useful when dealing with large-scale applications where maintaining clear and structured logs are essential.

The console.table() Method

The console.table() method in Node.js, is used for displaying the tabular data in an organized format. It is particularly useful when working with arrays of objects or large datasets where a structured view improves readability.

Example

const A = [
... {id:1, name:"BMW"},
... {id:2, name:"CIAZ"}
... ];
console.table(A);

Output

(index)	ID	Name
0	1	'BMW'
1	2	'CIAZ'

The console.time() and console.timeEnd() Methods

The console.time() and console.timeEnd() methods in Node.js are used to measure the time taken to execute a block of code. It is particularly useful for testing and optimization, helping the users to analyse the efficiency of their code.

Example

console.time("Loop Execution Time");
for (let x=0; x<250; x++){
... }
console.timeEnd("Loop Execution Time");

Output

Loop Execution Time: 17.078s