What are Event Listeners?
20 January, 2023
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In JavaScript, an event listener is a function executed in response to a specific event occurring on an element in the browser. An event listener is "attached" to an element, and the listener function is called when the specified event occurs on that element. Event listeners allow you to create interactive and dynamic web pages by responding to user input, such as a button click, a form submission, or a page load.
To attach an event listener to an element, you use the addEventListener() method, available on all DOM elements. The first argument to addEventListener() is the type of event you want to listen for (e.g., "click", "submit", "load"), and the second argument is the function that should be executed when the event occurs. For example:
var button = document.getElementById("myButton");
button.addEventListener("click", function() {
alert("Button was clicked!");
});In this example, an event listener is attached to the button element, listening for the "click" event. When the button is clicked, the function passed to addEventListener() will be executed, displaying an alert message.
The event listener function can also take an event object, which provides more information about the event, such as the target element, the type of event and the time of the event.
button.addEventListener("click", function(event) {
console.log(event.target); //log the button element
console.log(event.type); //log the event type 'click'
console.log(event.timeStamp);//log the time of the event
});It's also possible to remove the event listener as well.
button.removeEventListener("click", myFunction);Event listeners are a powerful feature of JavaScript that allows you to create interactive and dynamic web pages, and they are widely used in modern web development to create responsive and user-friendly interfaces.