Date Formate
Date Format has 3 type- ISO date
- Short date
- Long date
Statement
JavaScript statements are composed of- Values
- Operators
- Expressions
- Keywords
- Comments
| Statement | Type |
| var a, b, c; | // Declare 3 variables |
| a = 5; | // Assign the value 5 to a |
| b = 6; | // Assign the value 6 to b |
| c = a + b; | // Assign the sum of a and b to c |
Boolean
- JavaScript has a Boolean data type.
| Operator | Description | Example |
|---|---|---|
| == | equal to | if (day == "Monday") |
| > | greater than | if (salary > 9000) |
| < | less than | if (age < 18) |
Object
- Object can be store 3 type of datas.
var objectName= new Object();
Example :
<html>
<head>
<title>User-defined objects</title>
<script type="text/javascript">
// Define a function which will work as a method
function addPrice(amount){
with(this){
price = amount;
}
}
function book(title, author){
this.title = title;
this.author = author;
this.price = 0;
this.addPrice = addPrice; // Assign that method as property.
}
</script>
</head>
<body>
<script type="text/javascript">
var myBook = new book("Perl", "Mohtashim");
myBook.addPrice(100);
document.write("Book title is : " + myBook.title + "<br>");
document.write("Book author is : " + myBook.author + "<br>");
document.write("Book price is : " + myBook.price + "<br>");
</script>
</body>
</html>
Out put<html>
<head>
<title>User-defined objects</title>
<script type="text/javascript">
// Define a function which will work as a method
function addPrice(amount){
with(this){
price = amount;
}
}
function book(title, author){
this.title = title;
this.author = author;
this.price = 0;
this.addPrice = addPrice; // Assign that method as property.
}
</script>
</head>
<body>
<script type="text/javascript">
var myBook = new book("Perl", "Mohtashim");
myBook.addPrice(100);
document.write("Book title is : " + myBook.title + "<br>");
document.write("Book author is : " + myBook.author + "<br>");
document.write("Book price is : " + myBook.price + "<br>");
</script>
</body>
</html>
Book title is : Perl Book author is : Mohtashim Book price is : 100
Events
- some common HTML events
| Event | Description |
|---|---|
| onchange | An HTML element has been changed |
| onclick | The user clicks an HTML element |
| onmouseover | The user moves the mouse over an HTML element |
| onmouseout | The user moves the mouse away from an HTML element |
| onkeydown | The user pushes a keyboard key |
| onload | The browser has finished loading the page |
Arrays
- arrays are used to store multiple values in a single variable
- What is an Array?
- array is a special variable
- Array can hold more than one value at a time
Creating an Array
- var cars = new Array("Saab", "Volvo", "BMW");
- var cars = [ "Saab", "Volvo", "BMW"];
Access the Elements of an Array
- var cars = ["Saab", "Volvo", "BMW"];
- document.getElementById("demo").innerHTML = cars[0];
Output is Saab
Math Object
| Math.round(4.7); | returns 5 |
| Math.pow(8, 2); | returns 64 |
| Math.sqrt(64); | returns 8 |
| Math.abs(-4.7); | returns 4.7 |
| Math.ceil(4.4); | returns 5 |
| Math.floor(4.7); | returns 4 |
| Math.sin(90 * Math.PI / 180); | returns 1 |
| Math.cos(0 * Math.PI / 180); | returns 1 |
returns -200
Math.max(0, 150, 30, 20, -8, -200);
returns 150
Math.random();
returns a random number
Booleans
Boolean Values
- YES / NO
- ON / OFF
- TRUE / FALSE
Comparisons and Conditions
less than| == | equal to | if (day == "Monday") |
| > | greater than | if (salary > 9000) |
| < | if (age < 18) |
Functions
- When an event occurs (when a user clicks a button)
- When it is invoked (called) from JavaScript code
- Automatically (self invoked)
Function Return
- JavaScript reaches a return statement, the function will stop executing
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