In JavaScript, an event refers to an action or occurrence that happens during the execution of a program or user interaction with a web page. The event could be triggered by the browser, user, or a script, and examples of events are mouse clicks, mouse movements, key presses, form submissions, page loading, etc. Events are important in JavaScript because they allow developers to write code that responds to user interactions and other actions in real-time. To handle events, you can use event listeners, which are functions that get called when the event occurs. Here's an example in JavaScript:

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// select an element and assign an event listener to it
const button = document.querySelector('button');
button.addEventListener('click', function() {
  // code to run when the button is clicked
});

In JavaScript, an event is an action or occurrence that happens in the browser, such as a user clicking a button, a page finishing loading, or an error occurring. Events are used to trigger JavaScript code that responds to those actions or occurrences. To handle events in JavaScript, you can use event listeners which are functions that wait for the event to occur and then execute the code you specify. Here's an example of adding an event listener for a button click in JavaScript:

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const myButton = document.querySelector('#myButton');
myButton.addEventListener('click', function() {
  // code to execute when the button is clicked
});

You can find more information about events and event listeners in JavaScript in the following link: https://developer.mozilla.org/en-US/docs/Web/API/Event_Target/addEventListener

JavaScript events are triggers that initiate the execution of JavaScript code when a certain action occurs. Examples of actions that can trigger events include clicking a button, pressing a key, scrolling the page, hovering over an element, and submitting a form.

For example, when a user clicks a button, a click event is triggered. A keypress event is triggered when a user presses a key. Other events such as scroll, mousemove, focus, and blur, are also triggered when a user interacts with a web page.

In order to use JavaScript events, you must define a function in the code that will be executed when the event action occurs. This is known as an event handler. Some common JavaScript events and their event handlers include onclick, onchange, onkeypress, onmouseover, onsubmit, onfocus, and onblur. For example, to run a function when a user clicks a button, you would use the onclick event handler.

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document.getElementById("myButton").onclick = myFunction;

function myFunction() {
  console.log("The button was clicked!");
}

You can use JavaScript to create events that can execute code in response to user interactions. These events lie at the core of interactive websites. Here is a basic example of an event listener, waiting for a click event on an HTML element:

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document.getElementById("myButton").addEventListener("click", function () {
  alert("Button clicked!");
});

Other events can be used in JavaScript and you can read more about them in the MDN web docs article on events.

The code is written in JavaScript and makes use of DOM-related functions, such as document.querySelector to access and manipulate elements of the DOM.

The search() function is being triggered when the user submits the form, indicated by the event listener form.addEventListener set to submit. The purpose of the function is to take the value from the input with the id="city-input" and store it. The event.preventDefault() is then used to actually prevent the form from submitting, since we want to manage the input with JavaScript logic first.

When the value is stored, a conditional is used to check whether the input is empty or not. If it is empty, an alert of the value will be triggered. Otherwise, the innerHTML of h5 is changed to the value of the input.

This is how the code works overall.

For more information on how events work in JavaScript, you can refer to this link.

You can apply two functions, two alerts and two event listeners in Javascript using the addEventListener and removeEventListener methods.

For functions:

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function firstFunc() {
  // do something
}

function secondFunc() {
  // do something
}

For alerts:

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alert("First Alert");
alert("Second Alert");

For event listeners:

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//first Event listener 
document.addEventListener("click", firstFunc);

//second Event listener
document.addEventListener("click", secondFunc);

References:

-MDN web docs - addEventListener()

-MDN web docs - removeEventListener()

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.