DOJO session from the IT team at The Health and Social Care Information Centre - All you need to know about Java Script!

1. JAVASCRIPT DOJO
Lessons and thoughts
from DevWeek

2. TALKS ATTENDED
• “Modern JavaScript” - K. Scott Allen
• “Just because it’s JavaScript doesn’t give you
the right to write rubbish!” – Hadi Hariri
• Mobile development with MVC4 and jQuery
Mobile – Brock Allen

3. Nobody
knows
JavaScript!

4. DOUBLE AND TRIPLE EQUALS
a)1 == “1”
a)1 == true
a)“1” == true
a)1 == “ 1 “
a)1 == [1]
f) null == undefined
f) 1 == 1
f) “ “ == false
f) NaN == NaN
f) 1 == “true”

5. Prefer strict equals === to ==

6. QUNIT

7. SCOPE
A/
(function () {
if (true) {
var functionScope = "functionScope";
}
return functionScope;
})();
B/
var functionScope = "functionScope";
(function () {
return functionScope;
})();
C/
(function () {
var test = function () {
var functionScope = "functionScope";
}
return functionScope;
})();
D/
(function () {
var functionScope = 0;
var functionScope = “functionScope”;
return function
}

8. HOISTING
http://elegantcode.com/2010/12/24/basic-javascript-part-5-hoisting/

9. Function scope means that all
variables and parameters
declared inside a function are
visible everywhere within the
function.

10. FUNCTION DECLARATIONS
VS FUNCTION EXPRESSIONS
Function Declaration
function functionDeclaration() {
return “I’m a function declaration”;
}
Function Expression
var functionExpression = function() {
return “I’m a function expression”;
};

11. AUTOMATIC SEMICOLON
INSERTION
Using semicolons in JavaScript is optional BUT
JavaScript inserts them automatically.
Don't forget to use new on constructor functions.
New and This

12. TECHNIQUES
• Constructor protection
• Encapsulation
• Placing methods on the prototype
• Self executing functions
• Namespaces
• Module Pattern / Revealing module pattern

13. CONSTRUCTOR PROTECTION

14. STORE FUNCTIONS ON THE
PROTOTYPE

15. HADI HARIRI
• “It’s just JavaScript!”
• “JavaScript is write once code – you never want to go back to
it and change it”
• “People think that JavaScript is not maintainable.”
• “People think SRP doesn’t exist in JavaScript – how can a class
have a single responsibility if there isn’t a class”
• “We care in C#, we care in Java....why not JavaScript?”

16. NEXT STEPS
• Know JavaScript better.
• Be able to write and run tests easily in Visual
Studio.
• Write real world JavaScript tests with
mocking.
• Get intellisense in Visual Studio
• Be able to run tests as part of Team City build
• Have tools which will help me improve the

17. USEFUL LINKS
• K Scott Allen’s blog - www.odetocode.com/blogs/all
• Hadi Hariri , same talk in Norway – http://vimeo.com/43536490
• Basic JavaScript blog posts – http://elegantcode.com/2011/03/24/basic-
javascript-part-12-function-hoisting
• JavaScript sketch pad – http://jsfiddle.net
• Free Book (now published by O’Reilly) based on ECMAScript version 3
http://javascriptenlightment.com/JavaScript_Enlightenment.pdf
• JavaScript performance test bed – http://jsperf.com