1. Unit 20 - Client Side Customisation of Web Pages
Week 4 – Lesson 9
Fundamentals of Scripting

2. Fundamentals of Scripting Languages
Introduction
Characteristics
Uses
Scripting language constructs

3. Assignment 2 - Scripting Languages
What a scripting language is
How it works
What types are available
The main features
How does a scripting language improve functionality
Explain in detail how a browser implements a scripting language

4. Results 22 submissions, 4 missed 7 passes 15 referrals 5 merits
3 distinctions
15 referrals

5. P2 Definitions (10) 10 topics to describe Some missing altogether
Some incomplete –do you proof-read?
“…is shown in the image below.”

6. P2 Definitions (10) Should be original From a relevant source
quoted eg.
“scripting languages are designed for gluing: they assume the existence of a set of powerful components and are intended primarily for connecting components together.” John K. Ousterhout
IEEE Computer magazine, March 1998
topics
Event-driven & object-orientated
“scripting languages are designed for gluing: they assume the existence of a set of powerful components and are intended primarily for connecting components together.” John K. Ousterhout
IEEE Computer magazine, March 1998

7. P2 Definitions (10)
Should describe the feature – use an example where possible
‘more needed’ this is often why

8. Security Major issue is placing code to run on client’s machine
Cross-site scripting attacks XSS
Vulnerability present in about 70% pf web applications (sources, Veracode, Acunetix)

9. Security

10. XSS
Reflective XSS
Malicious Javascript in , victim clicks link, Javascript sent to vulnerable website, reflected back and run on victim machine.

11. Persistent attack
Attacker includes malicious script as part of user-name, other users view profile, code executes on other users machine

12. Constructs Need correct construction:
Syntax i.e. Grammar and order correct of words
Dot operator allows an object to use a method
Variable data stored as text or numbers
Must have unique name within script
Loops or iterations code which is executed repeatedly.

13. Objects A type of data which: Knows things about itself (properties)
Knows how to do things (methods)
Many objects already exist
Can create new ones

14. An example of ‘object’ code...
The ‘String’ object:
<script>
Hw=“Hello World”
document.write(Hw.length)
</script>
The output on the screen would be ’11’ ; the string called hw is eleven characters long (10 letters and a space).

15. Methods
Each object knows which methods it can carry out, eg (string object):
<script>
Hw=“Hello world”
document.write(Hw.toUpperCase())
</Script>
Copy this code and observe the screen output.
The method UpperCase forces the whole phrase to upper case.

16. Loops for - loops through a block of code a specified number of times
while - loops through a block of code while a specified condition is true
do...while - also loops through a block of code while a specified condition is true
for...in - loops through the properties of an object

17. Event handling An event that triggers a piece of code
Some examples and further explanation are here:

18. M2 Client vs server is not needed
Compare examples of object-orientated and event-driven
Explain how Javascript improves functionality:
Drop-down menus
Mouse-followers
Image galleries
Validation
Browser detection
Create cookies
Read/write/modify HTML elements
hiding or showing elements
moving elements
changing colors or fonts

19. D1 Understanding client-side scripting Sheryl Canter, April 2004