Output in JavaScript

In JavaScript, "output" means displaying information to the user or to the developer. There are multiple ways to show output depending on the situation — let’s explore them all!

1. console.log() – Developer Console Output

This is the most common way developers test and debug their code.

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

• Displays output in the browser's developer console.
• Great for debugging and checking values.
• Not visible to regular users on the webpage.

To see it:

• Open your browser → Right-click → Inspect → Console tab.

2. document.write() – Writing to the Page

This method writes directly into the HTML document.

document.write("This text appears on the page.");

• Simple and direct.
• Not used in real projects because it overwrites the whole page if used after it loads

3. alert() – Popup Message

This creates a popup box that displays a message.

alert("This is an alert box!");

• Easy way to show a quick message.
• Can be annoying for users if overused.
• Blocks interaction until the user clicks "OK"

4. Output to HTML Elements

You can display output by changing the content of an HTML element using innerHTML.

HTML:

<p id="output">

JavaScript:

document.getElementById("output").innerHTML = "Hello from JS!";
                  

• Best way to show output on the page without overwriting anything.
• Commonly used in real web applications.