Question

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JavaScript - a way check if an option of the < select> tag is selected

rated 0 times [ 6] [ 7] / answers: 1 / hits: 22348 / 14 Years ago, mon, march 7, 2011, 12:00:00

I have a select tag and I want to check if a moth is selected.

 <select name=Birth_Month>

    <option value= SELECTED>- Month -</option>

    <option value=January>January</option>

    <option value=Fabruary>Fabruary</option>

    <option value=March>March</option>

    <option value=April>April</option>

    <option value=May>May</option>

    <option value=June>June</option>

    <option value=July>July</option>

    <option value=August>August</option>

    <option value=September>September</option>

    <option value=October>October</option>

    <option value=November>November</option>

    <option value=December>December</option>

</select>

So do this:

if (document.registration_form.Birth_Month.value === '') 

{

    alert('Please fill select Month!');

}

But this JavaScript for some select-s work and for some of them, does not. Obviously, when the - Month - is selected the it returnes - Month - insted of (empty string). What I have done wrong? What is the best way of checking the tag's selection?

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raymondd

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answered 14 Years ago tiffany · Accepted Answer

Browsers didn't always have a .value property for <select> - we used to have to get the value of the <option>:

var birthMonth = document.registration_form.Birth_Month;

if (birthMonth.options[birthMonth.selectedIndex].value === '') {

  // something

}

I use jQuery .val() now. I don't remember which browsers lack the select.value property, and maybe those browsers are so old that we don't need to worry about them anymore. But jQuery doesn't use select.value - it loops through each of the options to find the selected option's value.

Of course, if you know you'll always have a single blank option as the first option, just check for selectedIndex==0.