JavaScript events are triggered by user interactions on a webpage like clicking a button, hovering a mouse over an element, or pressing a key. Each event carries information like which element was interacted with, which key was pressed, or what was the coordinates of the click. This information is used by the event handler to determine what action should be taken.

For instance, a click event on a button element might call a function that submits a form or toggles a modal. When a key is pressed, the event handler might call a function that focuses an input or performs a search.

To execute a function when an event is triggered, the syntax is usually like this:

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element.addEventListener("event", function(){
    // Do something...
});

For a complete list of events and more information, check out MDN Web Docs.

Objects in JavaScript are stored in key-value pairs, which allows you to store data in an organized way. To create a JavaScript object, declare a constructor function, define the properties and methods of the object and then instantiate the object. For example, here is a constructor function that defines an object called "Person":

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function Person(name, age) {
  this.name = name;
  this.age = age;
}

This constructor function defines two properties: name and age. You can then make an instance of this object using the new keyword:

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const person = new Person("John Doe", 30);

You can then access the values of this object using dot notation, e.g.

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console.log(person.name); // Output: John Doe

For more information about objects in JavaScript, see MDN's tutorial on objects.

The main difference between an array and an object in JavaScript is the way they store data. Arrays use numeric indices to access data and objects use named keys. Additionally, arrays preserve the order of the elements, while objects do not. For example:

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let arr = [1, 2, 3];
console.log(arr[1]); // Outputs 2

let obj = {x: 1, y: 2, z: 3};
console.log(obj.y); // Outputs 2

To use a variable that is inside another function, you have to define the variable outside the function and pass it as a parameter. This is known as passing the variable by reference.

For example, if you have the following JavaScript code:

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let outerVariable = 10;

function foo() {
  let innerVariable = 1;
  return outerVariable + innerVariable;
}

You can use the outerVariable inside of the foo function by passing it as a parameter when calling the function like this:

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console.log(foo(outerVariable)); // 11

This technique is very useful for when you need to use a variable from the outer scope inside a function.

For more information, see the JavaScript Scopes and Closures documentation from MDN.

When writing code in JavaScript, it is best to follow certain coding conventions. Some conventions to consider include:

*Running code in a logical order (from top to bottom). *Writing functions and variables in the same format and order. *Using indentation to represent different levels of the code. *Using CamelCase for naming functions. *Organizing the code into small blocks separated by blank lines. *Using constant values rather than hard-coded values. *Including comments to explain your code.

For more information, read this Guide to Coding Conventions.

Console logging is a way to print out debugging information to the console window in most modern web browsers. To console log, you can use the console.log() method. For example, in JavaScript you can use the following code to print a message to the console window:

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console.log('This message will display in the console');

If you are using JavaScript, you can use the if statement to check if the user has entered a value. This can be done by using the prompt() method and then using the ! operator to check if the value is truthy or not. If not, you can then use the alert() method to display a prompt to the user:

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let userInput = prompt('Please enter a value');

if (!userInput) {
  alert('No value was entered!');
}

The else keyword in Javascript is used to execute a statement when the condition of an if statement is false. For example, you can set the condition of an if statement with a comparison operator and then use an else statement to respond when the condition is false:

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if (x > y) {
  // run if condition is met
} else {
  // run if condition is not met
}

To add a property to an object, you can use the dot notation or the square bracket notation.

Using the dot notation, you can directly assign a value to the property as follows:

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// Dot notation
const obj = {};
obj.propName = 'Property value';

Using the square bracket notation, you can include variables and reserved words in the name of an object's property by wrapping the name of the property with quotes as follows:

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// Square bracket notation
const obj = {};
const propName = 'key';
obj[propName] = 'Property value';

For more information, see this article.

To select text in JavaScript, you can use the window.getSelection() method. This will create a Selection object which you can then use to set the start and end of the selection and make other modifications. A demo can be found here.

To remove an array in most programming languages, you can use the pop() or shift() command depending on whether you want to remove the first or last element in the array. For instance, in JavaScript, you can use the following command to remove the last element of the myArray array:

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myArray.pop()

For more information on these commands, please refer to the Mozilla Developer Network documentation.

You can use an array to set the innerHTML of an element to the correct day of the week by first declaring and initializing an array containing the days of the week. For example:

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let days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];

Then you can use the getDay() method to get the index of the day in the array, like so:

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let index = new Date().getDay();

Finally, you can use the calculated index value to access the appropriate day of the week string from the array, and set it as the value of the element's innerHTML:

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document.getElementById("elementId").innerHTML = days[index];

You can find more information on the getDay() here.

An array is a data structure consisting of a set of elements of the same type. Elements in an array are accessed using their numerical indices, which usually begin with 0 at the first element and increase by one for each element in the array. Each element of an array can be referred to as an object, as each object in an array holds a single value. Examples of objects in an array can include strings, integers, booleans, floats, or any other data type.

innerHTML is a JavaScript DOM property that can be used to get or set the HTML contents of an HTML element.

For example, if you wanted to change the content of a <div> or <p> element, you could do so using the innerHTML property, as in this example:

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document.getElementById("example-div").innerHTML = "This is the new content of the div";

This is the same concept as setting the innerText property. The difference is the innerHTML property allows the user to set values that include HTML tags, while the innerText value will not recognize HTML tags.

For more information, checkout this link: MDN Web Docs - innerHTML.

In JavaScript, you can use Math.floor() to round a number down to its nearest integer.

For example:

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let x = 7.82
Math.floor(x) // returns 7

For more information, please see the MDN documentation on Math.floor().

In JavaScript, the Math.round() method can be used to round a number to the nearest integer. For example:

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let num = 1.24;
let roundedNum = Math.round(num);

console.log(roundedNum); // 1

More information on the Math.round() method can be found here.

JSS (JavaScript Syntax Style) is a framework that allows developers to create their own styling format in JavaScript. This can be used to create custom components like buttons. You will need to use functions to properly format your button components using JSS. You can read more about JSS and how to use it for styling buttons here.

Adding an event listener to a button click can be done using JavaScript. The code below will add a listener to the button with the id myButton, and run the myFunction() when the button is clicked.

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document.getElementById("myButton").addEventListener("click", myFunction);

function myFunction() {
  // Your code here
}

More information regarding adding event listeners can be found on the Mozilla Developer Network documentation on event listener.

It depends on the particular situation. Generally speaking, forEach is more convenient to use when iterating over an array, and for loop is better suited for more complex iterative operations over an array. For more explanation, see this resource from Mozilla.

To create a loop using a programming language, you can use a for loop, a while loop, or a do-while loop. Below is an example in Java:

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for(int i = 0; i < 10; i++) {
   System.out.println(i);
}

This loop will start with the variable i equal to 0, then print the variable as long as it is less than 10, then increment the variable by 1 (i++) each time it loops.

In JavaScript, a document is an object that gives access to and manipulates the currently loaded HTML document. It is a part of the window global object, which represents the window of the current web page. A document object is generated by the browser. It is the root node of the document and it provides an interface for manipulation of the document structure like node trees and their contents. The document object also provides access to stylesheet information, such as style rules and linking elements.

Using query selector in JavaScript, you can select an element from the DOM (Document Object Model) by its ID, class, tag name, attributes, or a combination of these.

For example, to select an element with an ID of 'demo':

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const element = document.querySelector('#demo');

To select all elements with class 'test':

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const elements = document.querySelectorAll('.test');

More information can be found in the MDN documentation.

Code smell is a concept in software programming that refers to bad design of code that can make a program difficult to maintain, expand and refactor. Code Smells are usually not bugs, and do not affect the correctness of code, but don’t comply with best practices for writing the code, or making it easier to maintain, such as making the code more concise, efficient and readable. Examples of code smell include long functions, repetitive code, and deep nested looping.

Async/Await is a language construct that allows developers to write asynchronous code more easily. It is built into modern JavaScript (ES2017 and later) and is supported by TypeScript. Async/Await allows developers to write code that looks and behaves synchronously, but is actually asynchronous. This makes it easier for developers to read, write, and reason about their code. More info: MDN: Async functions

Bubbling in the DOM is an event propagation method. It starts with an event triggering on the innermost element and then proceeds to trigger the same event on its parent element and then its parent’s parent element and so on. This behavior is known as bubbling and propagates the same event through different elements on the DOM.