Writing first JavaScript program - Step-by-Step Execution

Concept Flow - Writing first JavaScript program

Start Program

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Write code: console.log('Hello, world!')

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Run code in browser or Node.js

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JavaScript engine executes code

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Output appears on console: Hello, world!

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Program ends

The program starts, runs the console.log statement, prints the message, then ends.

Execution Sample

Javascript

console.log('Hello, world!');

Prints the text 'Hello, world!' to the console.

Execution Table

Step	Action	Code Executed	Output
1	Start program
2	Execute console.log	console.log('Hello, world!');	Hello, world!
3	Program ends

💡 Program ends after printing the message.

Variable Tracker

Variable	Start	After Step 2	Final
No variables	-	-	-

Key Moments - 2 Insights

Why do we use console.log in this program?

console.log is used to show messages on the console. In the execution_table row 2, it prints 'Hello, world!' so we can see output.

Does this program change or store any data?

No, this program only prints a message. The variable_tracker shows no variables are created or changed.

Visual Quiz - 3 Questions

Look at the execution_table, what is printed at step 2?

A Nothing is printed

B Goodbye!

C Hello, world!

D An error message

💡 Hint

Check the Output column in execution_table row 2.

At which step does the program end?

A Step 3

B Step 1

C Step 2

D There is no end

💡 Hint

Look at the Action column and exit_note in execution_table.

If we change the text inside console.log to 'Hi!', what changes in the execution_table?

A Step 2 action changes to something else

B Output at step 2 changes to Hi!

C Program ends earlier

D No changes at all

💡 Hint

Focus on the Output column in execution_table row 2.

Concept Snapshot

JavaScript programs run code line by line.
Use console.log('text') to print messages.
The message appears in the console.
No variables needed for simple output.
Program ends after last line runs.

Full Transcript

This program shows how to write your first JavaScript code. It uses console.log to print 'Hello, world!' on the console. The execution flow starts the program, runs the console.log command, prints the message, then ends. No variables are created or changed. This is the simplest way to see output in JavaScript.