In answer to a previous question
I confidently said:
The need to rebuild in order to see changes in your Web components (CSS, JavaScript, HTML) did used to be an annoyance in early versions of what was then Worklight and is now MobileFirst. I forget when the need for a rebuild was removed but certainly in Worklight 6.2 and beyond you now simply need to refresh in your browser.
My personal practice is always to have Mobile Web environment in my project and then choose that from the Console. This loads the application in the browser-based Mobile Simulator that you can tailor to fit your target form-factor. This has a "Go/Refresh" button that immediately reflects your edits.
However I'm now working in 6.3.0.00-20150106-1717 and ... it seems to be necessary to rebuild and redeploy to see any changes to my HTML, CSS and JavaScript. In 6.2 things work as expected.
I am about to try a later version of Studio, thought it was worth asking that the referenced question had identified a defect.