Why I can't enable select html after disabling it?

Question

What's wrong with this code? When I change first select to International It disables the second select. but when I'm select Local it doesn't enable the second select

<script type="text/javascript">
function changetextbox()
{
    if (document.getElementById("LocalOrInternations").value == "International") {
        document.getElementById("NormalOrPaper").disabled='true';
    } 
  else
     document.getElementById("NormalOrPaper").disabled='false';
}
</script>

<span class="input-group-addon" id="basic-addon1">Local Or International</span>
<select name="LocalOrInternations" id="LocalOrInternations" onChange="changetextbox();" class="form-control">
    <option  value="Local">Local</option>
    <option value="International">International</option>
</select>

<span class="input-group-addon" id="basic-addon1">Normal Or Paper Seminar></span>
<select name="NormalOrPaper" id="NormalOrPaper" class="form-control">
    <option  value="Normal">Normal</option>
    <option value="Seminar">Seminar</option>
</select>

Code test

Answer 1

'false' and 'true' are strings . When coerced to boolean, they're both true (because any string that isn't blank is "truthy".) You want the actual booleans false and true (no quotes).

if (document.getElementById("LocalOrInternations").value == "International") {
    document.getElementById("NormalOrPaper").disabled = true;
    // -------------------------------------------------^^^^
} 
else {
    document.getElementById("NormalOrPaper").disabled = false;
    // -------------------------------------------------^^^^^
}

---

Side note: I recommend being consistent with your {} . Either include them around single statements (as you did with the if ), or don't (as you did with the else ), but don't sometimes include them around single statements and not other times.

Answer 2

you have to remove ' from the boolean tag.

you have to set like this.

<script type="text/javascript">
function changetextbox()
{
    if (document.getElementById("LocalOrInternations").value == "International") {
        document.getElementById("NormalOrPaper").disabled=true;
    } 
  else
     document.getElementById("NormalOrPaper").disabled=false;
}
</script>

check this jsfiddle: click here

Answer 3

这应该有帮助

document.getElementById("NormalOrPaper").removeAttribute('disabled');