document.designMode controls whether the entire document is editable. Valid values are "on" and "off". According to the specification, this property is meant to default to "off". Firefox follows this standard. The earlier versions of Chrome and IE default to "inherit". Starting in Chrome 43, the default is "off" and "inherit" is no longer supported. In IE6-10, the value is capitalized. 


var mode = document.designMode;
document.designMode = "on";
document.designMode = "off";


Make an <iframe>'s document editable:

iframeNode.contentDocument.designMode = "on";


Specification Status Comment
WHATWG HTML Living Standard
The definition of 'designMode' in that specification.
Living Standard Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Android Webview Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support (Yes) ? ? ? ? (Yes)

See also