1) The document discusses advanced JavaScript topics like hoisting, strict mode, functions as objects, prototypes, closures, and important JavaScript functions like call, apply, bind. 2) It provides examples of hoisting, strict mode, best practices for avoiding globals and type comparisons, and functions, objects, and prototypes. 3) Important JavaScript functions covered include timing functions like setTimeout and setInterval, global objects like window, location, and navigator, and newer JavaScript versions and APIs.

1. Advanced JavaScript
Dhruvin Shah

2. Agenda
• Hoisting and Strict Mode
• Functions as Objects
• Best Practices
• Objects and Prototypes
• Functions
• Closures
• Important Javascript Functions
• Javascript Global Objects
• Javascript Versions

3. Hoisting
• Moving declarations on top of the current
scope
• Only declarations and not initializations
• This can lead to errors and bugs in code if
unaware about variables
• Solution ?

4. Use Strict
• "use strict";
• Declared at the beginning of a script, it has
global scope
• Recognized only at the beginning of a script
• Introduced since ECMA 5

5. Best Practices
• Avoid Global variables
– Use strict mode to detect undeclared variables
– Use Closures
• Declarations and Initializations on top to avoid
undefined values
• Don’t declare type of variables
• Use === Comparison
• Don’t use eval()
• Try using for .. in instead of conventional for

6. Examples
var x = 5 + 7;
var x = 5 + "7";
var x = "5" + 7;
var x = 5 - 7;
var x = 5 - "7";
var x = "5" - 7;
var x = 5 - "x";
var x = 2 * "7";
var x = 2 * "x";

7. Objects and Prototypes
• Objects – Properties and Methods
• var person = {
firstName:"John",
lastName:"Doe",
age:50,
eyeColor:"blue“,
fullName: function(){
return this.firstName + “ ” +
this.lastName;
}

8. Functions
• Anonymous functions
e.g. var x = function (a, b) {return a * b};
• Self Invoking Function
e.g. (function () {
var x = "Hello!!"; // self invoke
})();
• Does not check the number of parameters
passed when invoked

9. Closures
• Global variables can be made local (private)
with closures.
function makeFunc() {
var name = 'Mozilla';
function displayName() {
alert(name);
}
return displayName;
}
var myFunc = makeFunc();

10. Important Javascript Functions

11. Call vs Apply vs Bind
Parameter Call Apply Bind
Definition calls a function with
a given this value
and arguments
provided
individually
calls a function with
a given this value,
and arguments pro
vided as an array
(or an array-like
object
Function gets
executed when
event is triggered
or some condition
is satisfied
Syntax function.call(thisArg
, arg1, arg2, ...)
fun.apply(thisArg,
[argsArray])
fun.bind(thisArg[,
arg1[, arg2[, ...]]])

12. • setTimeout(func, millisec) => returns ID
• clearTimeout(ID)
• setInterval(func, millisec) => returns ID
• clearInterval(ID)
• this variable is not accessible while using
Timing Events
• Solution ?
Timing Events

13. • window – open, close, moveTo, resizeTo
• screen – height, width, pixel depth
• location –
window.location.href
window.location.hostname
window.location.pathname
window.location.protocol
window.location.assign
• history – back, forward
• navigator – browser information
Javascript Global Objects

14. • Device API
− Light sensor
− Battery
− Geolocation
− Device Orientation
− Screen Orientation
• Communication API
− Notification
− Network
• Data management
Web API

15. JavascriptVersion

16. • Arrow Functions
• Typescript
Further Reading
Sources
• W3schools.com
• Mozilla Developer network