MutationRecord: target property

Value

The Node that the mutation affected.

If the record's type is attributes, this is the Element whose attributes changed.
If the record's type is characterData, this is the CharacterData node.
If the record's type is childList, this is the Node whose children changed.

In the following example, there are two divs: a red div (#red-div) and a blue div (#blue-div), inside a container div #container. A MutationObserver is created to observe the container. The observer is observing changes to the childlist, and also has subtree: true so it will observe changes to the children of the container's children.

The observer callback logs the target of the mutation record. When we add nodes to the #red-div or the #blue-div, the target will be the #red-div or the #blue-div, respectively.

HTML

html

<pre id="log">Target of mutation:</pre> <button id="add-nodes-to-red-div">Add a node to red div</button> <button id="add-nodes-to-blue-div">Add a node to blue div</button> <button id="reset">Reset</button> <div id="container"> <div id="red-div"></div> <div id="blue-div"></div> </div>

#log { border: 1px dotted black; padding: 0.5rem; } #red-div { border: 1px solid red; margin-top: 0.5rem; margin-right: 0.5rem; padding: 0.5rem; overflow: auto; } #blue-div { border: 1px solid blue; margin-top: 0.5rem; margin-left: 0.5rem; padding: 0.5rem; overflow: auto; } #container { display: grid; grid-template-columns: 50% auto; }

JavaScript

const container = document.querySelector("#container"); const redDiv = document.querySelector("#red-div"); const blueDiv = document.querySelector("#blue-div"); const addToRed = document.querySelector("#add-nodes-to-red-div"); const addToBlue = document.querySelector("#add-nodes-to-blue-div"); const reset = document.querySelector("#reset"); const log = document.querySelector("#log"); addToRed.addEventListener("click", () => { const newPara = document.createElement("p"); newPara.textContent = `Current time: ${Date.now()}`; redDiv.appendChild(newPara); }); addToBlue.addEventListener("click", () => { const newPara = document.createElement("p"); newPara.textContent = `Current time: ${Date.now()}`; blueDiv.appendChild(newPara); }); reset.addEventListener("click", () => self.location.reload()); function logMutationTarget(records) { for (const record of records) { log.textContent = `Target of mutation: ${record.target.id}`; } } const observer = new MutationObserver(logMutationTarget); observer.observe(container, { childList: true, subtree: true });