File | Settings | Debugger | Live Edit
The page is available only when the LiveEdit bundled plugin is enabled. By default the plugin is active. If not, enable it in the Plugin Configuration Wizard or on the Plugins page of the Settings dialog box.
|Highlight current element in browser on caret change||When this check box is selected, the browser highlights the area that represents the code you are currently editing in WebStorm.|
In this area,
configure the way changes made to the code during a debugging session are applied.
Note that an update will now be performed only if none of the modified files have any syntax errors.