1 00:00:00,360 --> 00:00:05,490 Hello welcome to the section on object oriented programming here's what we'll be doing in this section 2 00:00:05,490 --> 00:00:05,950 . 3 00:00:06,150 --> 00:00:12,000 We're going to define what object oriented programming or O.P. is and revisit the new keyword and understand 4 00:00:12,000 --> 00:00:13,630 it in quite a bit of depth. 5 00:00:13,860 --> 00:00:18,990 We'll then use constructor functions to reduce code duplication and refactor our constructors using 6 00:00:18,990 --> 00:00:20,100 call and apply. 7 00:00:20,400 --> 00:00:25,450 If you haven't watched a series on the keyword this I highly recommend that you do that first. 8 00:00:25,590 --> 00:00:30,840 Everything in these videos will build all of our knowledge of the key word this as well as call apply 9 00:00:30,990 --> 00:00:31,920 and bind. 10 00:00:31,920 --> 00:00:32,800 Here we go. 11 00:00:33,330 --> 00:00:35,450 So what is object oriented programming. 12 00:00:35,460 --> 00:00:41,970 Simply put it's a programming model based around the idea of objects and blueprints which create objects 13 00:00:42,480 --> 00:00:47,580 we call these blueprints classes and the objects that we create from our classes are traditionally called 14 00:00:47,670 --> 00:00:50,650 instances in object oriented programming. 15 00:00:50,790 --> 00:00:56,220 We strive to make our classes abstract and modular so that we can reuse classes easily and share them 16 00:00:56,220 --> 00:00:58,680 amongst all parts of an application. 17 00:00:58,710 --> 00:01:04,140 Javascript does not have built in support for classes unlike languages like Python Ruby and Java. 18 00:01:04,370 --> 00:01:10,980 We can mimic the behavior of classes by using Javascript has functions and objects before we see how 19 00:01:10,980 --> 00:01:13,910 to use functions to mimic the behavior of water classes. 20 00:01:14,040 --> 00:01:17,610 Let's see why this programming technique is quite useful. 21 00:01:17,610 --> 00:01:22,040 Imagine for a second that you're an architect and you're tasked with building 4 houses. 22 00:01:22,230 --> 00:01:27,440 Each house is going to have a number of bedrooms bathrooms as well as a number of square feet. 23 00:01:27,450 --> 00:01:30,690 The first thing that might come to mind is let's make an object for each house. 24 00:01:30,690 --> 00:01:32,010 We need to make. 25 00:01:32,190 --> 00:01:37,710 Seems pretty reasonable but once we start having to create more than a few objects things get very repetitive 26 00:01:37,830 --> 00:01:38,940 and tedious. 27 00:01:39,510 --> 00:01:43,830 Let's refactor this code by reading a blueprint for what a house should look like. 28 00:01:44,100 --> 00:01:49,380 Let's make a function that when used we'll construct a house object in javascript. 29 00:01:49,380 --> 00:01:52,650 We call the special functions constructor functions. 30 00:01:52,650 --> 00:01:56,100 Now let's see what our constructor function for a house looks like. 31 00:01:56,340 --> 00:01:59,790 Right off the bat we see that the name of the function is capitalized. 32 00:01:59,790 --> 00:02:01,950 This doesn't change anything about the function. 33 00:02:02,040 --> 00:02:06,960 It's just best practice and convention so that other developers know that this is a constructor function 34 00:02:06,960 --> 00:02:07,900 . 35 00:02:07,920 --> 00:02:11,250 The next thing we see is that the keyword this is back. 36 00:02:11,250 --> 00:02:12,900 Just when you thought you were done with it. 37 00:02:13,050 --> 00:02:15,680 If you haven't wants that series please go back and do so. 38 00:02:15,840 --> 00:02:20,110 Otherwise the rest of the series will be quite confusing in this function. 39 00:02:20,110 --> 00:02:25,170 We're attaching properties onto the keyword this we're somehow hoping that when we call the function 40 00:02:25,410 --> 00:02:30,170 a new object will be returned to us with the values specified in this function. 41 00:02:30,190 --> 00:02:32,070 However something's missing here. 42 00:02:32,070 --> 00:02:37,140 If we look at the first house variable we are setting it equal to the result of the house function being 43 00:02:37,140 --> 00:02:38,070 called. 44 00:02:38,070 --> 00:02:41,460 The problem is our house function is not returning anything. 45 00:02:41,550 --> 00:02:43,840 Therefore the function will return undefined. 46 00:02:44,130 --> 00:02:45,690 So how do we fix this issue. 47 00:02:45,690 --> 00:02:49,710 The answer lies in another special keyword that will explore in the next video. 48 00:02:49,770 --> 00:02:50,820 The new keyword. 49 00:02:50,880 --> 00:02:51,650 See you there.