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JS Forms

JS Forms Forms API

JS Objects

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JS Functions

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JS HTML DOM

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JS AJAX

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JS JSON

JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Parse JSON Stringify JSON Objects JSON Arrays JSON PHP JSON HTML JSON JSONP

JS vs jQuery

jQuery Selectors jQuery HTML jQuery CSS jQuery DOM

JS Examples

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JS References

JavaScript Objects HTML DOM Objects


JavaScript Output


JavaScript Display Possibilities

JavaScript can "display" data in different ways:

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

Using innerHTML

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

The id attribute defines the HTML element. The innerHTML property defines the HTML content:

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Web Page</h1>
<p>My First Paragraph</p>

<p id="demo"></p>

<script>
document.getElementById("demo").innerHTML = 5 + 6;
</script>

</body>
</html>
Try it Yourself »

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


Using document.write()

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

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Web Page</h1>
<p>My first paragraph.</p>

<script>
document.write(5 + 6);
</script>

</body>
</html>
Try it Yourself »

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

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Web Page</h1>
<p>My first paragraph.</p>

<button type="button" onclick="document.write(5 + 6)">Try it</button>

</body>
</html>
Try it Yourself »

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



Using window.alert()

You can use an alert box to display data:

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Web Page</h1>
<p>My first paragraph.</p>

<script>
window.alert(5 + 6);
</script>

</body>
</html>
Try it Yourself »

Using console.log()

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

You will learn more about debugging in a later chapter.

Example

<!DOCTYPE html>
<html>
<body>

<script>
console.log(5 + 6);
</script>

</body>
</html>
Try it Yourself »