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.

Example

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 26
Full support 26
No support 18 — 26
Prefixed
Prefixed Requires the vendor prefix: webkit
Edge Full support YesFirefox 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 11Opera Full support 15Safari Full support 7
Full support 7
No support 6 — 7
Prefixed
Prefixed Requires the vendor prefix: webkit
WebView Android ? Chrome Android Full support 26
Full support 26
No support 18 — 26
Prefixed
Prefixed Requires the vendor prefix: webkit
Edge Mobile ? 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 15Safari iOS Full support 7
Full support 7
No support 6 — 7
Prefixed
Prefixed Requires the vendor prefix: webkit
Samsung Internet Android ?

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.

 

Document Tags and Contributors

Contributors to this page: Sheppy
Last updated by: Sheppy,