JavaScript Examples
JavaScript is the programming language of the web. You can use it to add dynamic behavior, store information, and handle requests and responses on a website.
JS, is a high-level, interpreted programming language that conforms to the ECMAScript specification. It is a programming language that is characterized as dynamic, weakly typed, prototype-based and multi-paradigm.
Alongside HTML and CSS, JavaScript is one of the core technologies of the World Wide Web.[9] JavaScript enables interactive web pages and is an essential part of web applications. The vast majority of websites use it,[10] and major web browsers have a dedicated JavaScript engine to execute it.
The Document method getElementById() returns an Element object representing the element whose id property matches the specified string. Since element IDs are required to be unique if specified, they're a useful way to get access to a specific element quick
JavaScript Can Change HTML Content
One of many JavaScript HTML methods is getElementById().
This example uses the method to "find" an HTML element (with id="demo")
and changes the element content (innerHTML) to "Hello JavaScript":
My first javascript
<!DOCTYPE html>
<html>
<body>
<h2>My First JavaScript</h2>
<button type="button"
onclick="document.getElementById('demo').innerHTML = Date()">
Click me to display Date and Time.</button>
<p id="demo"></p>
</body>
</html>
Light Bulb
<!DOCTYPE html>
<html>
<body>
<h2>What Can JavaScript Do?</h2>
<p>JavaScript can change HTML attribute values.</p>
<p>In this case JavaScript changes the value of the src (source) attribute of an image.</p>
<button onclick="document.getElementById('myImage').src='pic_bulbon.gif'">Turn on the light</button>
<img id="myImage" src="pic_bulboff.gif" style="width:100px">
<button onclick="document.getElementById('myImage').src='pic_bulboff.gif'">Turn off the light</button>
</body>
</html>
External Scripts
<!DOCTYPE html>
<html>
<body>
<h2>External JavaScript</h2>
<p id="demo">A Paragraph.</p>
<button type="button" onclick="myFunction()">Try it</button>
<p>(myFunction is stored in an external file called "myScript.js")</p>
<script src="myScript.js"></script>
</body>
</html>
myScript.js
function myFunction() {
document.getElementById("demo").innerHTML = "Paragraph changed.";
}
Variable and operators
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Variables</h2>
<p id="demo"></p>
<script>
var price1 = 5;
var price2 = 6;
var total = price1 + price2;
document.getElementById("demo").innerHTML =
"The total is: " + total;
</script>
</body>
</html>
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