Cannot set property 'selectedIndex' of undefined

Question

I am having select tag
How to access document elements and assign the value?

After executing this I get this error

Uncaught TypeError: Cannot set property 'selectedIndex' of undefined

This is my JavaScript code

  let gender = document.getElementsByClassName('genderClass');
  gender[0].selectedIndex = 2;

This is my HTML code

     <html>
        <body>
           <select class="genderClass" >
             <option  size="7" value="">Gender</option>
             <option  size="7" value="M">Male</option>
             <option  size="7" value="F">Female</option>
             <option  size="7" value="T">Transgender</option>
           </select>
        </body>
      <html>

can some one please help me.

the code you posted is not the code that is responsible for that error - your browser developer tools should tell you which line of your code is responsible for that error - if not, use a better browser — Jaromanda X, Mar 19 '20 at 05:30
OT however, your gender list is quite limited. Do you really need to ask? — danblack, Mar 19 '20 at 07:21

Akash Bhardwaj · Answer 1 · 2020-03-24T07:27:04.077

0

Firstly, check if gender[0] is defined and is an object. If yes, try this:

gender[0]['selectedIndex'] = 2;

By the way, gender[0].selectedIndex = 2; should also work if gender[0] is defined and is an object.

Update: Adding your script after the <body></body> tag might solve your problem.

edited Mar 24 '20 at 07:27

answered Mar 19 '20 at 05:39

Akash Bhardwaj

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that is my question already it is saying that gender[0] is undefined but how is it possible i defined it in html – ZaihamM Code Mar 19 '20 at 05:42
it is saying that gender[0] is not defined but how its possible? and if it is not defined how to define it? – ZaihamM Code Mar 19 '20 at 05:45
try adding a breakpoint at let gender = document.getElementsByClassName('genderClass'); and then check the value – Akash Bhardwaj Mar 19 '20 at 05:51
I have updated my answer, please check. If it solves your problem, please mark it as accepted. – Akash Bhardwaj Mar 20 '20 at 08:57

Cannot set property 'selectedIndex' of undefined

1 Answers1