.which vs js code example

Example 1: javascript vs java

/*
JavaScript: Easier to learn and run, runs in browser,
not strictly object-orientated, mainly client-side.

Java: More secure, strict OOP, steeper learning curve, 
used literally everywhere, needs to be compiled.
*/

Example 2: javascript !! vs !

// !! used for checking availability of data 
!!'hello' // true