알면 좋은 자바스크립트 간단한 팁,

true == 1; //true! (converts true to bit value 1)

true - false === 1 //true!!!

"2" + 2; //22!
"2" - 2; //0
"2" - - 2; //4
NaN == NaN; //false - this one sort of makes sense since NaN is any non-Number cast to a number
NaN  NaN; //false - whatever!
"" == 0 //true
undefined == null //false!
"0" == 0 //true!
"false" = false //false!!!'
'\t\r\n ' == 0 //true!!!
if(-1) {....} //true
if("") {....} //false
if("null") {....} //true