Event: eventPhase property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers.
The eventPhase read-only property of the
Event interface indicates which phase of the event flow is currently
being evaluated.
Value
Returns an integer value which specifies the current evaluation phase of the event flow. Possible values are:
Event.NONE(0)-
The event is not being processed at this time.
Event.CAPTURING_PHASE(1)-
The event is being propagated through the target's ancestor objects. This process starts with the
Window, thenDocument, then theHTMLHtmlElement, and so on through the elements until the target's parent is reached. Event listeners registered for capture mode whenEventTarget.addEventListener()was called are triggered during this phase. Event.AT_TARGET(2)-
The event has arrived at the event's target. Event listeners registered for this phase are called at this time. If
Event.bubblesisfalse, processing the event is finished after this phase is complete. Event.BUBBLING_PHASE(3)-
The event is propagating back up through the target's ancestors in reverse order, starting with the parent, and eventually reaching the containing
Window. This is known as bubbling, and occurs only ifEvent.bubblesistrue. Event listeners registered for this phase are triggered during this process.
Example
HTML
<h4>Event Propagation Chain</h4>
<ul>
<li>Click 'd1'</li>
<li>Analyze event propagation chain</li>
<li>Click next div and repeat the experience</li>
<li>Change Capturing mode</li>
<li>Repeat the experience</li>
</ul>
<input type="checkbox" id="chCapture" />
<label for="chCapture">Use Capturing</label>
<div id="d1">
d1
<div id="d2">
d2
<div id="d3">
d3
<div id="d4">d4</div>
</div>
</div>
</div>
<div id="divInfo"></div>
CSS
div {
margin: 20px;
padding: 4px;
border: thin black solid;
}
#divInfo {
margin: 18px;
padding: 8px;
background-color: white;
font-size: 80%;
}
JavaScript
let clear = false;
const divInfo = document.getElementById("divInfo");
const divs = document.getElementsByTagName("div");
const chCapture = document.getElementById("chCapture");
chCapture.addEventListener("click", () => {
removeListeners();
addListeners();
clearDivs();
});
clearDivs();
addListeners();
function removeListeners() {
for (const div of divs) {
if (div.id !== "divInfo") {
div.removeEventListener("click", onDivClick, true);
div.removeEventListener("click", onDivClick, false);
}
}
}
function addListeners() {
for (const div of divs) {
if (div.id !== "divInfo") {
if (chCapture.checked) {
div.addEventListener("click", onDivClick, true);
} else {
div.addEventListener("click", onDivClick, false);
div.onmousemove = () => {
clear = true;
};
}
}
}
}
function onDivClick(e) {
if (clear) {
clearDivs();
clear = false;
}
if (e.eventPhase === 2) {
e.currentTarget.style.backgroundColor = "red";
}
const level =
["none", "capturing", "target", "bubbling"][e.eventPhase] ?? "error";
const para = document.createElement("p");
para.textContent = `${e.currentTarget.id}; eventPhase: ${level}`;
divInfo.appendChild(para);
}
function clearDivs() {
for (let i = 0; i < divs.length; i++) {
if (divs[i].id !== "divInfo") {
divs[i].style.backgroundColor = i % 2 !== 0 ? "#f6eedb" : "#cceeff";
}
}
divInfo.textContent = "";
}
Result
Specifications
| Specification |
|---|
| DOM # ref-for-dom-event-eventphase③ |
Browser compatibility
| desktop | mobile | server | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
eventPhase
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support