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.

This can be done with JavaScript by creating a prompt, storing the value in a variable, and then creating a alert with the variable.

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let result = prompt("What do you want to be alerted");
alert(result);

You can use the alert() function to display a message in the form. For example, you can use the following JavaScript code to alert the value of the password input when the form is submitted:

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    document.getElementById("myForm").addEventListener("submit", function(event){
      alert("Password: " + document.getElementById("password").value);
      event.preventDefault();
    });

The alert() method of the window object in JavaScript displays an alert dialog with a message and an OK button. It has the following properties:

• message: A string containing the text to display in the dialog.
• modal: (optional) A boolean value indicating whether the alert dialog should be modal (true) or not (false).
• button: (optional) A string indicating what text should be displayed on the button (default is "OK").

For a Java alert message, you could use the following code:

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JOptionPane.showMessageDialog(null, "Your desired message");

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window.onload = function() {
  var applicantName = prompt("Please enter your first name", "");
  if (applicantName !=null && applicantName != "") {
    alert("Welcome, " + applicantName);
  } else {
    alert("Too bad for you");
  }
}

The following JavaScript code will alert the value of the password input when a form is submitted:

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document.querySelector('form').onsubmit = () => {
  alert(document.querySelector('input[type="password"]').value);
}

More information about forms can be found in this MDN article.

In JavaScript, the target property of a Event object identifies the element that initiated an event. When a certain event is triggered on a certain element, the target property of the Event object is set to that element. This property can be used to tell the origin of the event.

For example:

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<h1 onclick ="alertEvent(event)">
  Click me
</h1>

<script>
function alertEvent(e){ 
   alert(e.target.innerHTML);
} 
</script>

In the above example, when the h1 is clicked, the onclick event will be triggered. As a result, the alertEvent() function will be called and the target property will be set to h1, allowing you to use the e.target.innerHTML statement to retrieve the text of the h1, that is, "Click me".

Learn more:

• MDN - Event.target
• JavaScript Kit - Event Object Properties

In JavaScript, you can create a code that says "I love you" every time the user clicks on anywhere on the page by attaching an event listener to the document object:

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document.addEventListener('click', function(){
    alert('I love you');
});

Here, we attach an event listener to the document object using addEventListener. We define the type of event as click and the function that is executed whenever the click event occurs is alert('I love you').

For more information on how to use the addEventListener, please refer to this tidy guide by W3Schools.

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()

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function travel() {
    let name = prompt("What is your name?");
    let email = prompt("What is your email?");
    let travel = prompt("Do you enjoy traveling?");

    if (travel === "yes") {
        alert("Thank you " + name + "! I'll be in touch via email 😁");
    }
    else if (travel !== "yes") 
        alert("Thank you " + name + "! We won't bother you with emails at the moment, but if you change your mind, let us know!");
}

You can create a button in HTML using the following code snippet:

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<input type="button" value="Click Me!" onclick="alert('Hello world!')" />

This code will create a button that says "Click Me!" and when clicked an alert "Hello world!" will show on the screen.

For more detailed information see: How to Create a Button in HTML.

You can use the String.prototype.toLowerCase() in JavaScript to ignore case when comparing user-input.

Take a look at the example below:

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let country = prompt("Where are you from?")

if (country.toLowerCase() == 'brazil' || country.toLowerCase() == 'portugal') {
  console.log('Greetings!');
}

String.prototype.toLowerCase() will convert brazil, Brazil, BRAZIL to brazil so that the comparison of country will match with either brazil or portugal.

References: MDN String.prototype.toLowerCase()

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!');
}