Undefined Problem

Question

Hey guys...
In javascript how to say if the variable is undefined then do nothing or print nothing?
I tried the line below but it didn't work!

If ( typeof txt === 'undefined' ) {
Txt= null;
}

It still prints the undefined!!! Please help!!

Answer 1

var a;
if a==undefined
do something

Answer 2

if (!txt) {
//do something
}

Answer 3

Shaghayegh Hp , you have used three === and put a string, 'undefined'. Either put 2 equal tos or remove the quotes.

Answer 4

Arnesh thanks it worked

Answer 5

x==null try this 👶 with the if condition

Answer 6

Arnesh here is my code, it still dosent work. and prints"undefined"

https://code.sololearn.com/WUE0oR3HX6Z3/?ref=app

Answer 7

Shaghayegh Hp , remove the typeof

Answer 8

Arnesh it still dosent work!! 🤦‍♀️

Answer 9

typeof work with ()

Ex-
Console.log(typeof(5));

//number

Answer 10

Divya Mohan it still dosent work, maybe the other part of my code has a problem, did you check it?

Answer 11

What do you want as result that not executing here.

Answer 12

Divya Mohan how i can avoid this code from printing "undefined" after adding five comment?

Answer 13

Shaghayegh Hp , you didn't say that... :-)

https://code.sololearn.com/W2FRgWaHL2sm/?ref=app

Answer 14

How could be the typeof txt be undefined.
It will be always a string that's inside promt box or no comment .
Then why are you making a condition for

typeof(txt)=== 'undefined'

what do you want after clicking button 2

Answer 15

I am not a javascript person but I think it is also a case sensitive language for which you have to be sure that the Txt!=txt.
Moreover, I respect your question but, you could check it by printing in the if the condition to get sure about the condition.

Hope you understand what I mean.
And after correction please mention that if there is == or === in javascript as I believe there must be two equals and the text has to be in a string like "undefined".