a =1 일때
a == 2 false
a == 1 true
a == "1" true
a === 1 true
a === "1" false
a != 2 true
a !== 1 false
a !== "2" true
a !== 2 true
variablename = ( condition ) ? value1 : value2
var getScore = ( score < 5 ) ? low : high
score가 5 이하면 low 그렇지 않으면 high