WEB TECHNOLOGIES UNIT-3 | Degree 4th sem BCOM Computers web technologies unit-3 full explanation💯✅

追加: 2026-05-31

[00:00:00]Hello dear students, welcome back to our YouTube channel Learn with Sahira. In this video, we are going to see the complete and easy explanation of unit number three from the subject of web technologies, which is for degree fourth semester B.Com computer application students. After watching this one single video, I can confidently say you that you will become perfect in unit number three. So, definitely watch the video till the very end. And if you're new to our YouTube channel Learn with Sahira, please subscribe it for more exam preparation videos. Students, one important thing, I have personally prepared damn sure important question and answers notes for all subjects and languages of degree fourth semester.

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[00:01:17]Students, question number one is define data type. Explain the data type supported by JavaScript. Please try to understand that in JavaScript, a data type simply tells what kind of value we are storing in a variable. What is a variable? Variable is a placeholder or container. So, what value we are storing in that variable, we will be coming to know with the help of data type. We can create a variable, students, and we can store different types of values. Like we can store numbers, a text, a true or false. So, data type will help the computer to understand what kind of data it is, how to use it. For example, if the value is a number, we can do calculations. If it is a text, we can combine or display it. So, in JavaScript, we don't need to mention the data type separately. The language automatically understands it based on the value. But, we need to understand what are different data types, right?

[00:02:09]So, let us try to understand. First, it is number data type. Number data type is used to store numeric values, okay?

[00:02:16]These can be whole numbers or these can be decimal numbers. So, JavaScript treats both the same, okay? We can use numbers if you want to do cal calculations, okay?

[00:02:26]Uh when we want marks or prices, we will be using number data type. Example, if we store 10 and 5.5, we can add them and get 15.5. So, that is number data type.

[00:02:37]Here, we also have example, just have a look. Then, we have string data type. It is used to store text or characters, okay? Text is always written inside quotes. So, we can use single quotes or double quotes. We use strings for names, uh messages, addresses, and all. We can also join two strings together, okay?

[00:02:56]For example, first name is there, last name is there. We can combine them and we can create a full name.

[00:03:02]Then, we have boolean data type, students. Boolean stores only two values, true or false. It is mainly used for checking conditions, okay? For example, if age is greater than 18, true. If not, false. So, boolean helps in decision making, basically. Then, we have object data type. Object is used to store multiple related values together.

[00:03:21]Instead of creating many variables, we can store everything in one place. For example, a student can have name, age, course. So, all these can be stored inside one object. So, object will help to organize the data in structured way.

[00:03:35]Then, we have undefined data type.

[00:03:37]Undefined means a variable is created, but no value is given yet. For example, if we create a variable, but don't assign anything, it will be undefined.

[00:03:46]So, it will show that the variable exists, but value is not set. Then, we have null data type. Null means the variable has no value on purpose. It is different from undefined. Okay, don't get confused. Undefined means value not given. Null means value is intentionally empty. So, we use null when we want to clear or reset a value. Okay? Please try to understand.

[00:04:07]Number for numbers, string for text, and boolean for true or false, object for group of values, undefined no value yet, null means empty value intentionally.

[00:04:17]So, yes, data type tell us what kind of value a variable holds and they will help JavaScript to handle data correctly. Students, if you want in detail explanation answers which are very easy and simple to understand, you can message me on my Instagram.

[00:04:32]In my notes, you will be finding very easy and simple answers that if you just give a reading, you will understand the whole concept. You will get ready for your examination. These notes from where I'm explaining you are short notes prepared by me in order to provide you free explanation on YouTube, but paid notes are different. If you want them, message me on my Instagram.

[00:04:51]Question number two is, what is an operator? Explain the types of operators available in JavaScript. Students, in JavaScript, an operator is used to perform some action on values. Okay?

[00:05:03]Whenever we want to add numbers, compare values, check conditions, we will be simply using operators. For example, if we write 5 + 3, here plus is an operator and it adds the two values. So, operator is simply a symbol that does some work on the data. Then we have types of operator in JavaScript. Students, first we have arithmetic operators. Arithmetic operators are used for mathematical calculations. Okay? Arithmetic calculations we will be using this operator. So, we use them when we are working with numbers basically. Students, we have plus addition, subtraction, this asterisk is multiplication, this is division, this modulus is in order to provide or in order to find the remainder. So, if we have two numbers, we can easily perform calculations using these operators. Then we have comparison operators, students.

[00:05:55]These are used to compare two values, okay? The result will always be true or false. Boolean value dega hame. So, these are mainly used in conditions, okay? You can see this is greater than, this is less than, this is equals to, this is not equals to. So, if we compare 10 and 5 is 10 greater than 5? Yes, true. Is 10 less than 5? No, it is not. So, it will give you false.

[00:06:23]Then we have assignment operators, students. These are used to assign values to variables, okay? The basic one is Let me show you where it is.

[00:06:34]It will be equals to. The basic is equals to. This assigns the value, okay?

[00:06:38]Example, x equals to 5. There are also short forms like plus equals to, add and assign, minus equals to, subtract and assign, multiply equals to, multiply and assign. So, instead of writing full calculation, we can write it short form, okay? For example, x plus equals to 3 means x plus 3. Okay. So, basically this will make code shorter and easier, we can say. Then we have logical operators, students. These are used to combine the conditions, okay? Sometimes we need to check more than one condition at a time, right? So, for that we will be using these operators. We have this and and operator, then or operator, then not operator, okay? And, or, not.

[00:07:22]See, if the if both conditions must be true, we will be using and. If we use or, only one condition needs to be true.

[00:07:32]When we use not, it is used to reverse the result, okay? Basically this. Dobi conditions are the true and cut the possible condition true or cut the. If you want to reverse that result, we will be using not. Then we have string operator students, string operator is used to join text values. Okay, in JavaScript we use plus. Okay, we will be using this operator to combine the strings. For example, first name plus last name equals to full name. So instead of numbers here plus is used to for text we can say. So students, please try to understand. Let me say you again, arithmetic calculations comparison values to check karne ke liye hai.

[00:08:11]Assignment values ko store karne ke liye hai.

[00:08:14]Then we have logical conditions ko combine karne ke liye hai.

[00:08:19]String to join the text. I hope you understood. Then our third question is explain in detail about the math object in JavaScript. Students, in JavaScript the math object is used to perform mathematical calculations easily. Okay, as simple as that. Normally, if we want to do calculations, we write our own logic, right? But JavaScript already provides many ready-made functions inside the math object. Okay? So instead of writing everything from the beginning, scratch se likhne ke likhne se achha hai, we will be directly using these functions. Jo already inbuilt functions hai. So we don't need to create the math object, students. It is already available in JavaScript. Let us try to understand important methods.

[00:08:59]First we have maximum value which will be written in this way. The TK here is our code. So this method is used to find the largest number from given values. Okay, if we have many numbers and we want to know which one is the highest, we will be using this. You can have a example here. We are having these many numbers.

[00:09:18]And now this code will or this function will help you to find the highest number. What is the highest number here?

[00:09:25]Here it is 25. So in the output we will be getting 25. So it helps in finding highest marks, highest price, etc. and all. Highest find karna hai. Highest ka opposite hai minimum method, students.

[00:09:37]This method is used to find the smallest number. Okay, if we give multiple values, it will return the lowest one.

[00:09:43]You have the example that you can 10 25 59. The lowest guy here is eight. So I will put my home eight I got. So it is useful when we need minimum value. Then we have round students. Around is used to round a number to the nearest integer. Okay.

[00:09:57]If we have decimal, okay, if the decimal is 0.5, I got round round up. So it will increase.

[00:10:05]Yeah, I got use curry. I got 0.5 more 0.5 or more it will increase. 0.5 or less it will decrease. For example, you have to take all students.

[00:10:16]4.6 here. Open 5 minute at the 4.3 here.

[00:10:20]You need to 4 minute at the okay. So it will give the nearest whole number up and down but you have no good sector.

[00:10:26]Then we have ceiling method students.

[00:10:28]This method always rounds the number up.

[00:10:31]You put curry now here. Okay, this method always rounds the number up. Even if the decimal is very small, we still increase it. Okay, for example, 4.2 here. So it will become five. Okay, so it always goes to the next highest number. I have 3.5 here. So 4 minute at the 5.9 here. So 6 minute at the 5.1 here. So we 6 minute at the okay. It always up highest number related. You have the floor was called opposite here students. This method always rounds the number down. Okay, it removes the decimal part and it gives the lower value. If 4.9 here, so 5 minute at the 4 minute at the 3.5 here.

[00:11:07]So 4 minute at the 3 minute at the to upload difference some Joe ceiling method me number but that floor method me number niche at the okay.

[00:11:17]Then we have random method students.

[00:11:19]This is used to generate a random number between zero and one. Okay, every time we run it, we get a different value.

[00:11:27]Basically, it is used in games and random selection lotteries and all. So basically, it will help us when we need unpredictable values. Then, we have square root method, students. It will be a mathematical function, which is used to find square root of a number.

[00:11:41]Square root of 25 will be 5.

[00:11:44]5 into 5 is 25. 2 into 2 is 4. So, square root find going to 4 then we will get 2.

[00:11:51]Example If we have 625, we will be getting 25 because 25 into 25 will be 625. Like that square root method. So, here students, why it is useful or why it is important? Because math object makes calculations faster, easier, and more accurate. We don't need to write complex logic. We can directly use this method.

[00:12:13]Okay, it is widely used in calculations, games, data analysis, and all. Now, we have our question number four. What is our question number four? Define conditional statement. What are the different types of conditional statements in JavaScript? Students, in JavaScript, a conditional statement is used to make decisions. Okay, in real life also, we take decisions based on conditions, right? Like example, if marks are greater than 35, pass. Else, fail. Same idea is used in programming also. So, conditional statements help the program to decide what action to take based on a condition. The condition will always give a result, student. True or false. So, based on that result, the program will execute it different code.

[00:12:56]First type is if statement, students.

[00:12:58]This is used when we want to check only one condition. Okay, if the condition is true, the code inside will execute. If it is false, nothing happens. Okay?

[00:13:08]Example look. If Suppose if age is greater than 18, then show eligible. We are voting for the age of 20. Is this age greater than 18?

[00:13:22]Greater than 18. It is true.

[00:13:24]Eligible for vote.

[00:13:25]I will give it.

[00:13:27]Basically, our condition is true.

[00:13:36]>> Then we have if else statements students. This is used when we have two possible outcomes, okay? One block runs if the condition is true and another block will run if it is false. For example, if marks are greater than or equal to 35, pass.

[00:13:53]Fail so one of the two will always execute.

[00:13:57]Okay, other if condition true hey, so it's not block of code run over. It's not your head will run over ignore over.

[00:14:05]Other if condition false as I am sure it's not block of code run over it's not block of code run over ignore over.

[00:14:11]Other marks 35 hey yeah 35 say greater than hey to pass.

[00:14:15]35 say greater than hey to it's not block of code run over. Other marks 35 say less hey to year run over ignore over year run over okay. To guys I be it's not it's not run over ignore over.

[00:14:26]Then we have else if statements students. This is used when we have multiple conditions. The program will check conditions one by one. As soon as one condition becomes true it will execute that block and stop checking for other.

[00:14:38]Some show for example if the marks are greater than or equal to 90, grade eight. Grade A. If marks are greater than equal to 60, grade B. Else get a grade C they do. To year condition check over other year true hey to it's not ignore over it's not next condition it's not check over. Year other true hey to year ignore over year ignore over year execute over.

[00:15:03]Do we false hey to it's not execute over. Multiple conditions it's not check over. We have six statements students.

[00:15:10]This is used when we have many possible values for when variable writing many if else conditions we use switch to make it simpler, okay?

[00:15:18]Basically it will check the value that matches it with the cases students.

[00:15:21]Example, I will give you. If day equals to one, Monday if day equals to two, Tuesday then you have to open break default default default other Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday so it directly jumps to the matching case. Next step Monday, Tuesday, Wednesday, Thursday, Friday I can do simple look some Joe if you ask them.

[00:15:49]One condition if else two conditions else if multiple conditions switch many values of one variable.

[00:16:00]Okay, so yeah explanation why conditional statements are important students they grow it will control the flow of the program. It helps us to make decisions and it helps us to handle different situations. So yes conditional statements help the programs to make decisions by executing different codes based on the conditions we can say.

[00:16:19]Students we have a question number five.

[00:16:21]What is an event? Explain the event handling mechanism on a web page an event means something that happens.

[00:16:27]Okay, this can happen in two ways when a user does something or when the browser does something. Do we possible reasons or for example clicking a button typing in a text box moving the mouse page loading. So all these are nothing but events. So whenever something happens on the web page and the program reacts to it. That is called as event without events a web page will just show the content students. It will not respond to the user. We have few different types of common events. Let us see click event.

[00:16:54]It happens when the user clicks on something. Okay, this is one of the most used events. For example clicking a button to submit a form or clicking a link to open another page. So whenever we want an action on click, we will be using this event. Then we have mouse over event. This happens when the mouse pointer moves over an element. Okay, as soon as the pointer touches that element the event is triggered. For example changing the color of text, showing a drop-down menu. So, this is about this type. Then, we have key press event, students. This happens when the user presses key on the keyboard. It is mainly used when the user is typing, entering the data in the text box.

[00:17:30]Detecting user input is not nothing but the examples. Load event, students. This happens when the web page is fully loaded. As soon as the page is ready, the event is triggered. For example, showing a welcome message or running some code automatically. Yes, these are examples. Now, let us talk about event handling mechanism. First, it is event occurrence.

[00:17:49]First, the event happens, okay? It can be user action like clicking or typing or browser action like page load. So, this is the starting point. Then, the event detection. Next, the browser will detect that an event has happened, okay?

[00:18:01]It will understand which event occurred on which element. So, the browser will identify the action. Then, we have event handling. After detecting, the program will perform an action. This action is written using a function or a code, okay? Like showing a message, changing color, displaying content. These are the examples. So, basically, this step decides what should happen after that event. Uh then, if we talk about the simple flow, we can say that first event happens. Browser will detect it. Then, program will respond to it. Now, why this is important, students? Because it will make web page interactive. It will respond to the user actions. It will improve user experience. So, without event handling, the page or web page cannot react to user input, we can say.

[00:18:41]This was the complete explanation. How was the complete explanation? Let me know in the comment section. For notes, message me on my Instagram. Join our Telegram channel for more important updates. Do check out our playlist for all explanation videos. Playlist link, Instagram link, Telegram link, all links are available in this video description.

[00:18:57]All the very best. Bye-bye.