 The students in this module, we will look at a bit of housekeeping to put your house in order. House is the code and we will look at number of things which on the face of it may seem to be very simple, but they have a tremendous impact. Let's start with the outline of the module. You see that we will talk about case sensitivity, we will talk about white space, we will talk about comments and we will also talk about semicolon. So bear with me and you will be having some wonderful useful tips also at your disposal. So JavaScript is case sensitive. Case sensitive means that if you have say for example the while command, the while reserved word and it is all in lower case, it is fine. But if it's an uppercase or if the W is capital, then you may encounter some errors which are hard to debug. Okay, so that is one issue. So the reserved words in JavaScript are in lower case, but you can have a combination of uppercase and lowercase variable names in your code. So as you can see over here that there is a number of options of using different variable names. So you have this capital over here and you have this capital over here and all capitals. But remember that a variable name cannot start with a numeral. Okay, so with this in mind we move to the next slide. Now we look at the importance of white space. Now the code which you see over here, this code and this code over here, they are both same. They are both same, they are identical. But this is very difficult to read, difficult to read. Why it's difficult to read because over here when I add the space over here, this makes it readable. Okay, why because the thing is that after a couple of time or maybe weeks or months or years, the code becomes very difficult to understand if it's not properly spaced. Understand and you have to be visiting this code. You write, writing it takes less time, very less time but you might be using it for years. So you need to add the white space over here. Now look at the comments. Now there are different ways of writing the comments. This is one way of writing the comment. We have these box over here or this is multiple lines. This is multi-line. This is a single line comment over here. And this is another combination of the comments. So creating readable code and maintaining that code over a long term comments are your friends. Code that seems obvious now won't be nearly so obvious in the next time when you look at it, especially if a lot of time has passed. Understand. So you have this multi-line comments over here and you have the single line comments over here. Now try to understand, although they are all comments, but they have their utility in different domains also. For example, if you are explaining the code, if you are explaining the code in the beginning, then this is a better option. Why? Because you can make a lot of edits. You can make a lot of edits and changes over here and without having worrying about this thing. Understand. So the thing is that you can use the two slash method for small comments that spend one line or a few lines for large comments such as those at the beginning of a program or skip the multi-line comments style is a better choice because it makes adding or deleting the information very convenient. I hope you understand this. Now these are very small things, but remember comments are very, very important. They are very critical, especially with reference to the maintaining the code. Maintainers. Maintainers, code maintainers. For code maintainers, comments are very important and critical. Now let's look at the semi-colons. So in this slide, we will look at the semi-colons. Semi-colons delineate expression, separate them, but you have to be careful because JavaScript can insert semi-colons on its own. Now you actually wanted to write this, this you wanted, okay, but this you actually wrote, this you wrote and this semi-colon was inserted by JavaScript, by the JavaScript interpreter, okay, and this creates a problem over here. So you have to be careful because the JavaScript interpreter could not understand your intentions. That's the problem. Now if you are using semi-colon with if statement, you have to be careful because over here you put the semi-colon over here and it will just match this and do nothing. This code is not going to work. So you have to be careful. You won't use a semi-colon at the end of the if statement. The reason is that the statement or block of statements in opening and closing places that follows the condition is part of the condition statement. In this case the if statement, a semi-colon marks the end of the if statement and if improperly placed disassociates the first part of the if statement from the rest of the code. For example, the following code is wrong. The code within the braces will execute regardless of whatever is there. This is wrong. So that's all I have for this module.