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Fundamentals of Web Programming
Notes How to initialize a Local variable?
Any variable that is initialized inside a function using the var keyword will have a local scope.
If a variable is initialized inside a function without var, it will have a global scope. A local
variable can have the same name as a global variable.
var a = 10;
disp_a();
function disp_a()
{
var a = 20;
alert(“Value of ‘a’ inside the function “ + a);
}
alert(“Value of ‘a’ outside the function “ + a);
Self Assessment
Fill in the blanks:
9. To keep the browser from executing a script when the page loads, you can put your script
into a ...........................
10. A ........................... is an expression that defines an unnamed function.
11. An ........................... function saves us from rewriting the same code again and again and
helps us to make our application smaller.
12. The ........................... object is a local variable available within all functions.
13. ..........................variables exist only inside a particular function hence they have Local Scope.
8.4 Dialog Boxes
JavaScript supports three important types of dialog boxes. These dialog boxes can be used to
raise and alert, or to get confirmation on any input or to have a kind of input from the users.
Here we will see each dialog box one by one:
8.4.1 Alert Dialog Box
An alert dialog box is mostly used to give a warning message to the users. Like if one input field
requires to enter some text but user does not enter that field then as a part of validation you can
use alert box to give warning message as follows:
<head>
<script type=”text/javascript”>
<!—
alert(“Warning Message”);
//—>
</script>
</head>
Nonetheless, an alert box can still be used for friendlier messages. Alert box gives only one
button “OK” to select and proceed.
8.4.2 Confirmation Dialog Box
A confirmation dialog box is mostly used to take user’s consent on any option. It displays a
dialog box with two buttons: OK and Cancel.
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