removeUnnecessarySpaces

String.prototype.removeUnnecessarySpaces = function() {
    return this.split(/ +/).join(" ").trim()
}

// example
// code | expected output

"  t  e  s  t  i  n  g  ".removeUnnecessarySpaces() // "t e s t i n g"

"".removeUnnecessarySpaces()                        // ""
"testing".removeUnnecessarySpaces()                 // "testing"