Event: eventPhase property
==========================

 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`, then `Document`,
 then the `HTMLHtmlElement`, and so on through the elements
 until the target's parent is reached.
 Event listeners
 registered for capture mode when `EventTarget.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.bubbles` is `false`, 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 if `Event.bubbles` is
 `true`. Event listeners registered for this phase are triggered during this process.


Example
-------

### HTML


```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


```css
div {
  margin: 20px;
  padding: 4px;
  border: thin black solid;
}

#divInfo {
  margin: 18px;
  padding: 8px;
  background-color: white;
  font-size: 80%;
}
```

### JavaScript


```js
let clear = false;
let divInfo = null;
let divs = null;
let chCapture = null;

window.onload = () => {
  divInfo = document.getElementById("divInfo");
  divs = document.getElementsByTagName("div");
  chCapture = document.getElementById("chCapture");
  chCapture.onclick = () => {
    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 Standard # ref-for-dom-event-eventphase③ |

Browser compatibility
---------------------

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