how to check object contains key in javascript code example

Example 1: javascript does key exist

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

Example 2: how to check if object has key javascript

myObj.hasOwnProperty('key') // it checks object for particular key and not on prototype

Example 3: js object contain key

if ('key' in myObj)
// better
if (!myObj.hasOwnProperty('key'))

Example 4: typescript check if object has key

if ('key' in myObj)