JavaScript - When if statement is true, code doesn't execute?

Question

So I have 3 different inputs for the user - Day/Month/Year, and I'm trying to run an if statement to check if the month is Jan/Feb (1 or 2), and then if it subtracts 1 from the year. My if statement is:

if (month == 1 || month == 2) {
    if (month == 1) {
        year = Number(year) - 1;
    }
    else if (month == 2) {
        year = Number(year) - 1;
    }
}

This is my first time trying to use javascript and it's very frustrating! As you can see my code runs when I have month = 3, but as soon as I change it to 1 or 2 it no longer executes...

Or better yet put the code in the second screenshot into a Stack Snippet — Patrick Roberts
– Patrick Roberts, Commented Dec 6, 2018 at 17:50
@mahlatse and when question is edited, downvotes can be altered... — epascarello
– epascarello, Commented Dec 6, 2018 at 17:51

epascarello · Accepted Answer · 2018-12-06 17:56:21Z

4

It fails because you convert the year to a string and than after than you use string operations on the number. The error in your console should clearly state it.

year = Number(year) - 1
...
var century = year.substring(0,2)

so if you are going to do string actions on it, than you need to convert the number back to a string.

So either you do

year = (Number(year) - 1).toString()

or

var century = year.toString().substring(0,2)

In the end, the error "Uncaught TypeError: year.substring is not a function" should have been in your developer console.

edited Dec 6, 2018 at 17:56

answered Dec 6, 2018 at 17:51

epascarello

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CAGDAS AYDIN · Accepted Answer · 2018-12-06 18:10:53Z

-1

I've just try it on JSFidddle

$(document).ready(function(){

  var month=1;
  var year ='2018';


  if ((month == 1) || (month == 2)) {
        if (month == 1) {
            year = Number(year) - 1;
        }
        else if (month == 2) {
            year = Number(year) - 1;
        }   
    }
  alert(year);
});

JSFIDDLE LINK

answered Dec 6, 2018 at 18:10

CAGDAS AYDIN

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