Element: transitionstart event

Cú pháp

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("transitionstart", (event) => { })

ontransitionstart = (event) => { }

Event type

Một TransitionEvent. Inherits from Event.

Event properties

Also inherits properties from its parent Event.

TransitionEvent.propertyName Read only

Một chuỗi chứa the name CSS property associated with the transition.

TransitionEvent.elapsedTime Read only

A float giving the amount of time the transition has been running, in seconds, when this event fired. This value is not affected by the transition-delay property.

TransitionEvent.pseudoElement Read only

Một chuỗi, starting with ::, containing the name of the pseudo-element the animation runs on. If the transition doesn't run on a pseudo-element but trên phần tử, an empty string: ''.

Ví dụ

This code adds a listener to the transitionstart event:

element.addEventListener("transitionstart", () => {
  console.log("Started transitioning");
});

The same, but using the ontransitionstart property instead of addEventListener():

element.ontransitionstart = () => {
  console.log("Started transitioning");
};

Live example

Trong ví dụ sau, we have a simple <div> element, styled with a transition that includes a delay:

<div class="transition">Hover over me</div>
<div class="message"></div>

.transition {
  width: 100px;
  height: 100px;
  background: red;
  transition-property: transform, background;
  transition-duration: 2s;
  transition-delay: 1s;
}

.transition:hover {
  transform: rotate(90deg);
  background: transparent;
}

To this, we'll add some JavaScript to indicate where the transitionstart and transitionrun events fire.

const transition = document.querySelector(".transition");
const message = document.querySelector(".message");

transition.addEventListener("transitionrun", () => {
  message.textContent = "transitionrun fired";
});

transition.addEventListener("transitionstart", () => {
  message.textContent = "transitionstart fired";
});

transition.addEventListener("transitionend", () => {
  message.textContent = "transitionend fired";
});

The difference is that:

• transitionrun fires when the transition is created (i.e., at the start of any delay).
• transitionstart fires when the actual animation has begun (i.e., at the end of any delay).

Đặc tả kỹ thuật

Trình duyệt hỗ trợ

Xem thêm

• The TransitionEvent interface
• CSS properties: transition, transition-delay, transition-duration, transition-property, transition-timing-function
• Related events: transitionend, transitionrun, transitioncancel