Web/API/MutationObserverInit/characterDataOldValue

The MutationObserverInit dictionary's optional characterDataOldValue property is used to specify whether or not the MutationRecord.oldValue property for DOM mutations should be set to the previous value of text nodes which changed.

If you set the MutationObserverInit.characterData property to true but don't set characterDataOldValue to true as well, the MutationRecord will not include information describing the prior state of the text node's contents.

Character data changes are detectable on any text node, including nodes based on the Text, ProcessingInstruction, and Comment interfaces.

Syntax

var options = {
  characterDataOldValue: true | false
}

Value

A Boolean value indicating whether or not to set the MutationRecord's oldValue property to be a string containing the value of the character node's contents prior to the change represented by the mutation record.

By default, only changes to the text of the node specified as the target parameter when you called observe() are monitored. To watch for changes to the text contents of all descendants of target, set the subtree option to true.

If you set characterDataOldValue to true, characterData is automatically assumed to be true, even if you don't expressly set it as such.

Specifications

Specification	Status	Comment
DOMThe definition of 'MutationObserverInit.characterDataOldValue' in that specification.	Living Standard

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
characterDataOldValue	Chrome Full support 26 Full support 26 No support 18 — 26 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Edge Full support 12	Firefox Full support 14 Notes' Full support 14 Notes' Notes' Starting in Firefox 36, characterDataOldValue has no default value; previously, its default value was false.	IE Full support 11	Opera Full support 15	Safari Full support 7 Full support 7 No support 6 — 7 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	WebView Android ?	Chrome Android Full support 26 Full support 26 No support 18 — 26 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Firefox Android Full support 14 Notes' Full support 14 Notes' Notes' Starting in Firefox 36, characterDataOldValue has no default value; previously, its default value was false.	Opera Android Full support 14	Safari iOS Full support 7 Full support 7 No support 6 — 7 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Samsung Internet Android Full support 1.5 Full support 1.5 No support 1.0 — 1.5 Prefixed' Prefixed' Implemented with the vendor prefix: webkit

Legend

Full support  

Full support

Compatibility unknown  

Compatibility unknown

See implementation notes.'

See implementation notes.

Requires a vendor prefix or different name for use.'

Requires a vendor prefix or different name for use.

 

MutationObserverInit.characterDataOldValue by Mozilla Contributors is licensed under CC-BY-SA 2.5.