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Web Programming
Notes 5.1.2 Disadvantages of JavaScript
If you lack experience in programming, JavaScript will look daunting to you. Often, it is
not clear how the code works when you examine the HTML source. Long, complicated
Java scripts can add quite a bit of download time to your HTML page.
Although JavaScript is supported on the two major web browsers, there are a few
differences that may cause problems. Many of the graphic HTML creation tools do not
handle JavaScript very well.
Because the code executes on the users’ computer, in some cases it can be exploited for
malicious purposes. This is one reason some people choose to disable JavaScript.
Task “JavaScript validates data”. Is this a advantage or disadvantage? Analyze
5.1.3 Creating Our First Program in JavaScript
Save the Example 4.1 as MyExample.html and run it in same manner as HTML.
<html>
<body>
<script type=”text/javascript”>
document.write(“this is my first program!”);
</script>
</body>
</html>
Output
this is my first program!
Self Assessment
Fill in the blanks:
1. JavaScript is primarily a scripting language for use within ………………… pages.
2. A JavaScript can be used to validate form data before it is submitted to a …………………
3. Many of the graphic HTML creation tools do not handle ………………… very well.
5.2 JavaScript Data Types
A program can do many things, including calculations, sorting names, preparing phone lists,
displaying images, validating forms, ad infinitum. But in order to do anything, the program
works with the data that is given to it.
Data types specify what kind of data, such as numbers and characters, can be stored and
manipulated within a program. JavaScript supports a number of fundamental data types.
These types can be broken down into two categories, primitive data types and composite data
types.
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