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JavaScript : A trending scripting language
- 1. JavaScript “A simple way to get more.” Abhay Dhupar abhaydhupar123@gmail.com
- 2. What is JavaScript ? • JavaScript is one of the most popular and widely used programming language in the world right now. • It’s growing faster than other programming languages and big companies like Netflix, Walmart and Paypal build their entire applications around JavaScript. • • US offers 75000 dollars per annum to JavaScript developers on an average. • You can work as a - Front-end Developer Back-end Developer Full-stack Developer
- 3. What can you do with JavaScript ? • For a long time, JavaScript was only used in browsers to build interactive web pages. • Some developers referred to JavaScript as a toy language, but those days are gone because of huge community support and investments like large companies like facebook and google. • These days you can build - Web / Mobile Apps Command-line Tools Real-time Networking Apps Games
- 4. Where does JavaScript code run ? • JavaScript was originally designed to run only in browsers. So every browser has JavaScript Engine that can run JavaScript code. In Chrome, this engine is v8. • In 2009, a very clever engineer called Ryan Dahl took the open source JavaScript Engine in Chrome and embedded it in a C++ program. He called that program Node. • So Node is a C++ program which includes Google’s v8 JavaScript Engine. Now with this, we can run our JavaScript code outside of a browser. So we can pass our JavaScript code to node for execution. So with JavaScript, we can build the backend for our web and our mobile applications. • Browser and Node provide a runtime environment for our JavaScript code.
- 5. Let’s see JavaScript in action.
- 6. Editor and Other requirements • In order to write JavaScript code, you’ll need a code edit a code editor • Following are some of the commonly used - VS Code Sublime Atom
- 7. Download Node • Technically, you don’t need Node on your machine for learning JavaScript, as you can do in browser as well. • But it is good to have Node in your machine to install third party libraries.
- 8. JS through web browser <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <h1>Hello Abhay</h1> <script> console.log("Hello World") //Output(in your browser) inspect -> console </script> </body> </html>
- 9. Separation of Concerns • Now while we can easily write JavaScript code in between the script element. In a real-world application, you have thousands or even million lines of code. • We don't want to write all that code inline here we want to extract and separate our JavaScript code from our HTML code. • Let’s understand by a metaphor - Think of your house. In your bedroom, you have your bed and your clothes. • You don’t store your clothes in the kitchen. This is what we call separation of concerns. • We have the same principle in programming, so we want to separate HTML which is all about content from JavaScript which is all about behavior.
- 10. Cont…
- 11. JS through Node • Open your .js file location. • Open up cmd or terminal at same location. • Now write node file_name.js • Use Integrated terminal in VS Code.
- 12. Variables • We use variables to store data temporarily. • Use var keyword to declare a variable. • There are issues with var, we can also use let • Ex - var my_name = 'Abhay'; console.log(my_name); Rules • It cannot be a reserved word. • It cannot be start with a number. • It cannot contain a space or hyphen (–). We can either use CamelNotation. • It is case sensitive.
- 13. What type of value can we store ?
- 14. JavaScript : A Dynamic Language
- 15. Object • Object is a real world entity. • For example – instead of giving name, age of a person; we can create a person object. • Ex - let person = { name: 'Abhay', age: 30 }; // dot notation person.name = 'John'; // Bracket notation person['name'] = 'Mary'; console.log(person);
- 16. Arrays • Array in JS is also a object. • Sometimes in your application, you need to deal with list of objects. • So to store that list of objects, we need arrays. • Since JS is dynamic so size and data type in array can change in run time. • Ex – list of product, list of students. let array = ['Abhay','CSE'] array[2] = 1 console.log(array) console.log(array.length) console.log(typeof(array));
- 17. Functions • Functions are one of the fundamental building blocks in JS. • Functions are used to perform a task. • function keyword is used to declare a function. function greet(fname, lname) { console.log('Hello '+ fname + ' ' + lname) } greet('Abhay','Dhupar');