Why is this simple code giving an error?

Question

var d = new Date();
var day;
switch (d.getDay()) {
    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;
    default :
      day = "Saturday";
  }

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

This code seems to work for me - I get an "Monday" in the `day` variable. — Lix, Jul 09 '18 at 13:14
Provided that `#demo` exists, `document.getElementById("demo").innerHTML = "Today is : " + day;` — Gerardo Furtado, Jul 09 '18 at 13:14
I'm guessing the issue is `document.getElementById("demo")` returns undefined. — , Jul 09 '18 at 13:14
Uncaught TypeError: Cannot set property 'innerHTML' of null at myscript.js:27 #copied from console i.e. the last line — Vedant, Jul 09 '18 at 13:14
See the comment above from @Amy. That element doesn't exist when you try to set the innerHTML property. — Reinstate Monica Cellio, Jul 09 '18 at 13:15
@Archer - Your edit actually removes the "issue" that the OP is talking about (missing HTML element) - I've rolled back your edit FYI. — Lix, Jul 09 '18 at 13:16
@Lix - fair play. At the time it didn't and I didn't want to introduce an error so I added the element :p — Reinstate Monica Cellio, Jul 09 '18 at 13:17
I have used the demo id in the html file and saved this javascript file seperately — Vedant, Jul 09 '18 at 13:17
But *where* in the HTML are you referencing the js file? Before or after the element with that ID? — Gerardo Furtado, Jul 09 '18 at 13:18
Probably a case of needing to wait for the DOM to load before you modify it. Put the script tags at the bottom of the page - last thing inside the body tag. — Reinstate Monica Cellio, Jul 09 '18 at 13:18

score -1 · Answer 1 · answered Jul 09 '18 at 13:16

Add HTML and missing day and append at the end before assignment

var d = new Date();
var day;
switch (d.getDay()) {
  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;
  default:
    day = "Saturday";
}

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

<div id="demo"></div>

downvote for a valid solution without mention of what's wrong and what could be the improvement to the answer, not helping anyone. — Rikin, Jul 09 '18 at 17:22

Why is this simple code giving an error?

1 Answers1