The MutationRecord
read-only property previousSibling
is the previous sibling of an added or removed child node of the target
of a MutationObserver
.
The MutationRecord
read-only property previousSibling
is the previous sibling of an added or removed child node of the target
of a MutationObserver
.
If a node is added to or removed from the target
of a MutationObserver
, the value is the Node
that is the previous sibling of the added or removed node: that is, the node immediately before this one in the parent's childNodes
list.
The value is null
if there are no added or removed nodes, or if the node is the first child of its parent.
This adds a node every time you click the button. Then the observer logs the textContent
of the previousSibling
of the added node.
html
<button id="add-nodes">Add a node</button> <button id="reset">Reset</button> <pre id="log" class="log">Previous sibling of added node:</pre> <div id="target"><p>Node #0</p></div>
js
const addNodes = document.querySelector("#add-nodes"); const reset = document.querySelector("#reset"); const target = document.querySelector("#target"); let nodeNumber = 1; addNodes.addEventListener("click", () => { const newPara = document.createElement("p"); newPara.textContent = `Node #${nodeNumber}`; nodeNumber++; target.appendChild(newPara); }); reset.addEventListener("click", () => self.location.reload()); function logPreviousSibling(records) { for (const record of records) { if (record.type === "childList") { for (const newNode of record.addedNodes) { log.textContent = `Previous sibling of added node: ${newNode.previousSibling?.textContent}`; } } } } const observer = new MutationObserver(logPreviousSibling); observer.observe(target, { childList: true });
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
previousSibling |
16 | 12 | 14 | 11 | 15 | 7 | 4.4 | 18 | 14 | 14 | 7 | 1.0 |
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/MutationRecord/previousSibling