Ruby,Node.js真偽値を得る方法7選

ruby

puts (!0)
#=>false
puts (!1)
#=>false
puts (!!0)
#=>true
puts (!!1)
#=>true
puts (!"")
#=>warning string literal in condition
#=>false
puts (![])
#=>false
puts (!{})
#=>false

Node.js

console.log(!0)
//=>true
console.log(!1)
//=>false
console.log(!!0)
//=>false
console.log(!!1)
//=>true
console.log(!"")
//=>true
console.log(![])
//=>false
console.log(!{})
//=>false