One of the most important Q is how to check if the Java script object is undefined because lots of people do not know how to check but we will solve your this problem below,
Q – HOW TO CHECK IF A JAVASCRIPT OBJECT PROPERTY IS UNDEFINED
Ans – You have to javascript program and type in (typeof color //”undefined”) you will see easily your answer.
const list = []
const count = 2
typeof list //”object”
typeof count //”number”
typeof “test” //”string”
typeof color //”undefined”
There is one more Q which we have solved below for your help
Q2 – How To Create a Promise
Ans – It is very simple for creating a promise see below
As you can see the promise checks the done global constant, and if that’s true, we return a resolved promise, otherwise a rejected promise.
Using resolve and reject we can communicate back a value, in the above case we just return a string, but it could be an object as well.
3Q- What is a potential pitfall with using typeof bar === "object" to determine if bar is an object? How can this pitfall be avoided?
Answer – You can see the ans below
Q4
What is NaN? What is its type? How can you reliably test if a value is equal to NaN?
How to Change Example of Promise
Q – how to check if a variable exist in javascript?
Ans – If you want to know about the variable exist in javascript, see the below image will show you the your answer in simple method,
Q – what is JavaScript closures
