What is the exact difference between currentTarget property and target property in JavaScript?

javascript

event-delegation

event-propagation

event-handling

byAlex Kataev·Nov 18, 2024

event.target is the "trigger-happy" element that fired the event, while event.currentTarget is the "cool parent" overseeing the event listeners. Let's sit around a form and click some buttons:

// Listener on the form, like a hawk on a mouse
document.querySelector('form').addEventListener('click', (event) => {
  alert(`Target: ${event.target.tagName}`); // 'BUTTON', a wild button appeared!
  alert(`CurrentTarget: ${event.currentTarget.tagName}`); // 'FORM', the Pokedex in your pocket
});

Here event.target yell results in BUTTON, while event.currentTarget calmly notes down FORM. Witness the difference in action!

Unwrapping event properties

When confronted with the event.target, recognize the "instigator" or the element that launched the event. It'll stay the same throughout the bubbling or capturing stage. This maverick is especially helpful in event delegation where we associate the event listener to a parent and let the event bubble.

In stark contrast, event.currentTarget is your rock, the element to whom the event listener was actually hooked up. When tackling DOM hierarchies or flexible components, remember this trustworthy soul like your grandma's cookies recipe.

It's worth noting some events like focus and blur do not bubble, so target and currentTarget would be the same for these homebodies.

Caution: async handlers

As you journey with asynchronous event handlers, store a map of currentTarget. This step ensures that you will not be astray as the event object gets updated or overwritten throughout the event loop. Always remember, a competent web adventurer is a prepared web adventurer.

Rally your Promises or async/await skills in your event listener:

document.querySelector('form').addEventListener('click', async (event) => {
  const trustyForm = event.currentTarget; // Form the shield wall!
  await someLongWar();
  alert(`CurrentTarget: ${trustyForm.tagName}`); // The stronghold stands firm
});

Taming the browser beast

"Knowing is half the battle." If you've got your code tested on as many fronts as possible, like the ferocious Chromium 71, your quest for uniform event handling across distinct environments gains faithful allies.

Event mastery

A key to unlock the potential of JavaScript is to understand events. Dive into addEventListener and dispatchEvent methods and explore how target and currentTarget shape various landscapes of events. Refine your techniques to improve your event management patterns and write the legendary saga of your code's performance and readability.

React 17 changes

The landscape changes with React 17, as it challenges the need for evt.persist(). Yes, SyntheticEvent objects have declared independence and no longer requires pooling. This twist of fate means that event properties target and currentTarget are arms-length away, even asynchronously. A simple and comfortable freedom awaits your codewriting adventures in React.

Event bubbling and you

To become the event handler, decipher the way of the event propagation. Observe how the "current" in currentTarget marks the element managing the event. It’s an essential step if you seek to halt events with event.stopPropagation() or wish to devise complex strategies for event handling.

A skilled handler will cache event properties locally as soon as the event has been initiated and before any synchronous call.

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