Answers for "add key if value exists javascript"

Javascript key exists

var person={"name":"Billy","age":20}
person.hasOwnProperty("name"); // true
person.hasOwnProperty("sex"); // false

check if key does not exists in dictionary javascript

var person={"name":"Billy","age":20}
person.hasOwnProperty("name"); // true
person.hasOwnProperty("gender"); // false