Truncate a string to the closest word

gistfile1.js

// Truncate a string to the closest word
String.prototype.truncateToWord = function( length ) {
  return this
    .slice( 0, length + 1 )
    .split( /\s+/ )
    .slice( 0, -1 )
    .join( " " )
}

// Examples
// The ↓ marks the first character out of bounds.

//              ↓ 
"cut that shit out now!".truncateToWord( 15 ) // cut that shit

//            ↓ 
"cut that shit out now!".truncateToWord( 13 ) // cut that shit

//         ↓ 
"cut that shit out now!".truncateToWord( 10 ) // cut that