JavaScript Output

JavaScript can "display" data in different ways:

• Writing into an HTML element, using innerHTML or innerText .
• Writing into the HTML output using document.write() .
• Writing into an alert box, using window.alert() .
• Writing into the browser console, using console.log() .

To access an HTML element, you can use the document.getElementById(id) method.

Use the id attribute to identify the HTML element.

Then use the innerHTML property to change the HTML content of the HTML element:

Changing the innerHTML property of an HTML element is the most common way to display data in HTML.

To access an HTML element, use the document.getElementById(id) method.

Then use the innerText property to change the inner text of the HTML element:

Use innerHTML when you want to change an HTML element.

Use innerText when you only want to change the plain text.

For testing purposes, it is convenient to use document.write() :

Using document.write() after an HTML document is loaded, will delete all existing HTML :

The document.write() method should only be used for testing.

You can use an alert box to display data:

You can skip the window keyword.

In JavaScript, the window object is the global scope object. This means that variables, properties, and methods by default belong to the window object. This also means that specifying the window keyword is optional:

For debugging purposes, you can call the console.log() method in the browser to display data.

You will learn more about debugging in a later chapter.

JavaScript does not have any print object or print methods.

You cannot access output devices from JavaScript.

The only exception is that you can call the window.print() method in the browser to print the content of the current window.