js check if key is in object code example

Example 1: how to check if object has key javascript

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

Example 2: js object contain key

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

Example 3: typescript check if object has key

if ('key' in myObj)

Example 4: check object has key javascript

Object.prototype.hasOwnProperty()

Example 5: javascript if object has key

if('key' in object)

Example 6: js check if object key exists

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