Where to Learn Javascript

Javascript is a versatile language that can be used to build full-featured applications. But where do you start? Check out our roundup of the best resources to learn Javascript.

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Introduction: Why learn Javascript?

JavaScript is a versatile scripting language that can be used to add interactivity, animation, and other dynamic features to web pages. It is widely supported by web browsers and is relatively easy to learn. In recent years, JavaScript has become increasingly popular as a server-side scripting language for web applications.

The basics: variables, data types, operators, etc.

Any good programming language tutorial will cover the basics of the language. This usually includes an overview of:

-Variables
-Data types
-Operators
-Control flow
-Functions
-Arrays
-Objects
-Classes

Control flow: conditionals, loops, etc.

In computer programming, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative or a declarative program are executed or evaluated.

One way to express control flow is by means of flowcharts that graphically represent the order in which the individual statements, instructions or function calls of a program are executed.

Functions: declaration, invocation, etc.

In JavaScript, functions are objects. A function is a process that takes input, performs some operations on that input and then returns an output. Functions are written using the function keyword followed by a name, a list of parameters enclosed in parentheses and a block of code enclosed in curly braces. The block of code is the body of the function and it defines what the function does.

Functions can be defined in two ways: function declaration and function expression.

Function declaration:
A function declaration is when you write a function and give it a name. For example, the following code defines a function named myFunction that takes two parameters, x and y, and returns the sum of those two numbers.

function myFunction(x, y) {
return x + y; }

Function expression:
A function expression is when you write a function without giving it a name. For example, the following code defines an anonymous function that takes two parameters, x and y, and returns the sum of those two numbers. The anonymous function is assigned to a variable called myFunction.
var myFunction = function(x, y) { return x + y; }

Functions can be invoked or called by using their name followed by parentheses enclosing any required parameters. For example, to call the myFunction() declared above with values 3 and 4 for its x and y parameters respectively, we would write: myFunction(3, 4).

Objects and Arrays: working with data structures

Javascript offers several ways to create and manipulate objects for storing data. The two most common methods are through objects and arrays. In this article, we’ll explore how to work with both object and array data structures in Javascript.

Objects are one of the basic data structures in programming. They are used to store properties, or key-value pairs. A property is a value that is associated with a key, which can be used to identify it. In order to create an object, we use the {} notation.

var myObj = {
“key1”: “value1”,
“key2”: “value2”
};

We can also access object values using the dot notation.

myObj.key1 // returns “value1”
myObj[“key2”] // also returns “value2”
In the above example, we’ve created an object called myObj that has two properties: key1 and key2 . We can access these values by using either the dot notation or bracket notation.

Arrays are another data structure that is frequently used in programming. They are used to store a collection of items, which can be accessed by their index number. The items in an array do not have to be of the same type. In order to create an array, we use the [] notation.

var myArray = [1, 2, 3];
We can access individual elements in an array using their index number, which starts at 0 .

myArray[0] // returns 1
myArray[1] // returns 2
myArray[2] // returns 3

The Document Object Model: manipulating the DOM

The Document Object Model (DOM) is a representation of how a web page is organized. It consists of a tree of nodes, where each node represents an element on the page. The DOM can be manipulated with JavaScript to change the content or structure of a page.

The DOM is not part of the HTML or CSS standards, but it is developed by the W3C (World Wide Web Consortium). The DOM is supported by all major browsers, including Internet Explorer, Firefox, Safari, and Chrome.

##Document Object Model: manipulating the DOM
The Document Object Model (DOM) is a representation of how a web page is organized. It consists of a tree of nodes, where each node represents an element on the page. The DOM can be manipulated with JavaScript to change the content or structure of a page.

The DOM is not part of the HTML or CSS standards, but it is developed by the W3C (World Wide Web Consortium). The DOM is supported by all major browsers, including Internet Explorer, Firefox, Safari, and Chrome.

Events: responding to user input

Events are an important part of making any interactive web application. In fact, they are often the driving force behind user-driven applications. JavaScript provides a number of different events that can be applied to any element on a web page. These events allow you to respond to user input in a variety of ways.

Some of the most common events include:
-onload: when the page loads
-onunload: when the page unloads (leaves the site)
-onclick: when an element is clicked
-onmouseover: when the mouse cursor moves over an element
-onkeypress: when a key is pressed while an element has focus

You can respond to these events in a number of ways, including calling a function, changing the style of an element, or even opening a new window. In this tutorial, we’ll take a look at how to respond to some of these events.

Ajax: making asynchronous requests

In order to make asynchronous requests, we use the XMLHttpRequest object. This object is available in all modern browsers, and allows us to send and receive data without having to reload the page. In order to create a new XMLHttpRequest object, we use the following syntax:

var request = new XMLHttpRequest();

Once we have our request object, we need to open a connection. We do this by calling the open() method on our request object, and passing in two arguments: the type of request (‘GET’, ‘POST’, etc.), and the URL that we want to send our request to. For example:

request.open(‘GET’, ‘https://www.example.com/’);

Once we have opened a connection, we can send our request by calling the send() method on our request object:

request.send();

Error handling: dealing with problems

Javascript is a great language for building web applications, but one of the challenges of working with it is dealing with errors. When something goes wrong in your code, it can be tough to figure out what the problem is and how to fix it.

There are a few different ways to deal with errors in Javascript. One way is to use try/catch blocks. This lets you run a piece of code and if an error occurs, it will be caught and you can deal with it accordingly.

Another way to deal with errors is to use the debugger statements. These let you stop your code at a certain point and examine the state of your variables to see what went wrong.

Finally, you can also use logging to track errors. This can be helpful if you want to track down a problem after the fact or if you want to get more information about what went wrong.

No matter what method you choose, dealing with errors is an important part of working with Javascript. By taking the time to learn how to handle them properly, you’ll save yourself a lot of headaches down the road.

Advanced topics: closures, prototypes, etc.

Advanced topics in Javascript include closures, prototypes, and other advanced concepts. These topics can be difficult to understand, but there are many resources available to help you learn.

One great resource for learning about these topics is the “Javascript: The Good Parts” book by Douglas Crockford. This book covers the basics of Javascript and then diving into deeper topics such as closures and prototypes.

Another great resource for learning about these topics is the free online course “Javascript for Beginners” by Codecademy. This course covers the basics of Javascript and then gradually introduces more advanced concepts.

If you want to explore these topics further, there are many other resources available online and in libraries. With a little effort, you should be able to find everything you need to learn about these advanced topics in Javascript.