Running JavaScript using Node.js - Step-by-Step Execution

Concept Flow - Running JavaScript using Node.js

Write JavaScript file (e.g., script.js)

↓

Open terminal or command prompt

↓

Run command: node script.js

↓

Node.js reads and executes the file

↓

Output appears in terminal

↓

Program ends

This flow shows how you write a JavaScript file, run it with Node.js in the terminal, and see the output.

Execution Sample

Javascript

console.log('Hello from Node.js!');

This code prints a message to the terminal when run with Node.js.

Execution Table

Step	Action	Evaluation	Result
1	Start Node.js with script.js	Node.js loads script.js	Ready to execute
2	Execute console.log	Print string 'Hello from Node.js!'	Message shown in terminal
3	End of script	No more code	Program exits

💡 Script finishes after printing the message; Node.js process ends

Variable Tracker

Variable	Start	After Step 2	Final
console	object	object	object
console.log	function	function	function

Key Moments - 2 Insights

Why do I run 'node script.js' in the terminal?

Running 'node script.js' tells Node.js to read and execute your JavaScript file, as shown in execution_table step 1.

Why does the output appear in the terminal and not in a browser?

Node.js runs JavaScript outside the browser and prints output directly to the terminal, as seen in execution_table step 2.

Visual Quiz - 3 Questions

Look at the execution table, what happens at step 2?

A Node.js reads the file

B The message is printed to the terminal

C The program exits

D The terminal opens

💡 Hint

Check the 'Result' column in step 2 of the execution_table

At which step does the program finish running?

A Step 1

B Step 2

C Step 3

D After step 3

💡 Hint

Look at the 'Action' and 'Result' columns in the execution_table for when the program ends

If you change the message inside console.log, what changes in the execution?

A The output message in the terminal changes

B The program will not run

C Node.js will crash

D The terminal will not open

💡 Hint

Refer to the 'Evaluation' and 'Result' columns in step 2 of the execution_table

Concept Snapshot

Running JavaScript with Node.js:
1. Write your code in a .js file.
2. Open terminal and run 'node filename.js'.
3. Node.js executes the file and prints output to terminal.
4. Program ends when code finishes.
Use terminal to see results outside browser.

Full Transcript

To run JavaScript using Node.js, first write your JavaScript code in a file with a .js extension, for example, script.js. Then open your terminal or command prompt. Run the command 'node script.js' to start Node.js and execute your file. Node.js reads the file and runs the code inside. If your code uses console.log, the message will appear in the terminal. After the code finishes running, the Node.js process ends. This lets you run JavaScript outside a browser and see output directly in the terminal.