When I intalled one of the older verions (8.0.5) of WebStorm IDE on Mac OS X El Capitan and started it, I got an error saying saying that I need to install legacy Java SE 1.6 runtime.

webstorm-legacy-java-issue-1

Obviously I did not have Java 1.6 installed and did not plan to do so. Alternative approach here (the easiest for me) was to update WebStorm IDE configuration to accept newer verions of Java.

In order to do so, you need to update WebStorm Information Property List File. Make sure you backup your Info.plist file before any changes!

The property list file (Info.plist) file for the IDE is located under /Applications/WebStorm.app/Contents

The property list files contains an entry with key JVMVersion that has the following value: 1.6*. That value says that Java 1.6 is required.

WebStorm Info.plist JVMVersion

All needs to be done it to chage that property to something like 1.6+, which means that Java 1.6 or newer is required.

WebStorm Info.plist JVMVersion

After saving the changes the IDE started with no issue.