Meaning of javascript text between two slashes

Question

On Dreamweaver if I write on a Javascript document some text between two slashes like

Answer 1

It is the regular expression literal.

From w3schools:

var patt=new RegExp(pattern,modifiers);

or more simply:

var patt=/pattern/modifiers; 

And from MDN:

RegExp(pattern [, flags])

/pattern/flags