exclamation mark javascript code example

Example 1: es6 what is double exclamation operator

!oObject  // inverted boolean
!!oObject // non inverted boolean so true boolean representation

Example 2: javascript operator double not

// convert to boolean 
// The following examples are the only values which result in a false expression

!!0 // false
!!"" // false
!!null // false
!!undefined // false
!!NaN // false