Answers for "how to define key in an object after checking if data is available or not"

javascript does key exist

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

Posted by: Guest on July-22-2019

js check if object key exists

var obj = { key: undefined };
obj["key"] !== undefined // false, but the key exists!

Posted by: Guest on July-23-2020

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