No error, but the result is Undefined.javascript

Question

no errors in code but output get undefined

code

var xx = document.getElementById("stars").value;
var day;

switch (xx) {
  case 0:
    day = "Sunday";
    break;
  case 1:
    day = "Monday";
    break;
  case 2:
    day = "Tuesday";
    break;
  case 3:
    day = "Wednesday";
    break;
  case 4:
    day = "Thursday";
    break;
  case 5:
    day = "Friday";
    break;
  case 6:
    day = "Saturday";
}

document.getElementById("demo").innerHTML = "Today is " + day;

<p id="demo"></p>
<input type='hidden' id="stars" value='4'>

I have tried many ways but didn't get any solution please help me thanks in advance

Not a answer to you problem, just a tip. A better way to do the same is thing is to use an array like `arr = ["Sunday", "Monday", ...]` and then use `arr[day]` to access the value. — Maheer Ali, Jan 01 '21 at 09:49

Yousaf · Answer 1 · 2021-01-01T11:12:06.267

Switch statement uses strict equality comparison (===) to compare its expression against each case clause.

.value property returns a string. So value of xx, being a string, doesn't matches any case clause because value in each case clause is a number and strict equality comparison between values of two different types always evaluates to false. As a result, day is never initialized with a value other than its initial value of undefined

Changing the each case clause to a number will solve the problem

case "4":
    day = "Thursday";
    break;

Mureinik · Accepted Answer · 2021-01-01T10:34:31.743

1

value returns a string, and the values in your case expressions are numbers. One solution would be to use string literals there too:

var xx = document.getElementById("stars").value;
var day;

switch (xx) {
  case '0':
    day = "Sunday";
    break;
  case '1':
    day = "Monday";
    break;
  case '2':
    day = "Tuesday";
    break;
  case '3':
    day = "Wednesday";
    break;
  case '4':
    day = "Thursday";
    break;
  case '5':
    day = "Friday";
    break;
  case '6':
    day = "Saturday";
}

document.getElementById("demo").innerHTML = "Today is " + day;

<p id="demo"></p>
<input type='hidden' id="stars" value='4'>

edited Jan 01 '21 at 10:34

answered Jan 01 '21 at 09:47

Mureinik

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you mean `.value` returns a `string`. – apple apple Jan 01 '21 at 09:48
Hi the reason is bcuz yow `xx` has a "4" and you're switch has a 4 and as we know "4" !== 4 – Ernesto Jan 01 '21 at 09:53
@appleapple indeed, got caught up in the flow of writing. Thanks for noticing! Edited and fixed. – Mureinik Jan 01 '21 at 10:34

No error, but the result is Undefined.javascript

2 Answers2