Can someone help me understand why my JS code is not properly executing? Sorry I am newer at coding.

Question

Below is my code - when I execute it, it does not return the proper birth year if the user enters a month greater than 9. However if I remove the else if code, it DOES properly execute and returns the proper year even if the user enters a birth month greater than 9. Would someone please be able to help me figure out what I'm doing wrong?

var user = prompt("Please enter your name");
var user_age = prompt("Please enter your age");
var birth_month = prompt ("Please enter the number of the month you were born (ex. January = 1).");

if (birth_month > 9)
{birth_year = 2019 - user_age}

else if (birth_month == 9)
{var birth_day = prompt ("Please enter the day of your birth")}
if (birth_day > 13)
{birth_year = 2019 - user_age}
if (birth_day == 13)
{var birth_hour = prompt ("Please enter the hour of your birth")}
if (birth_hour > 8)
{birth_year = 2019 - user_age }

else (birth_year = 2020 - user_age)

document.write ("Hello ", user, "! <br>");
document.write ("Your age is: ", user_age, ". <br>", "This means the yea

Answer 1

Sorry the end it cut off is just the output:
document.write ("Hello ", user, "! <br>");
document.write ("Your age is: ", user_age, ". <br>", "This means the year of your birth is: ", birth_year);

Answer 2

Copy into playground paste link here..

I think, you are not covering birthmonth is less than 9..
Last if part belong to that's previous last if...

Answer 3

Document.write remove all previous context from document with what it have in it.

I suggest you to use document. innerHTML += "...... text here...... " ; instead of document. Write

Document. Write is used if you have to write only the things that is inside ( ) ;

Also you have syntex error with various "

Sorry the end it cut off is just the output:
document.write ("Hello ", user, "! <br>");

// this 👆 will not on screen only content of last document. Write will be there.

document.write ("Your age is: "+user_age+ ". <br>"+ "This means the year of your birth is: "+ birth_year);