Checking Value of Radio Button Group via JavaScrip

问题:

This may seem silly and downright stupid but I can't seem to figure out how to check the value of a radio button group in my HTML form via JavaScript. I have the following code:

<input type="radio" id="genderm" name="gender" value="male" />
<label for="genderm">Male</label>
<input type="radio" id="genderf" name="gender" value="female" />
<label for="genderf">Female</label>

How do I retrieve the value of gender via JavaScript?

回答1:

If you are using a javascript library like jQuery, it's very easy:

alert($('input[name=gender]:checked').val());

This code will select the checked input with gender name, and gets it's value. Simple isn't it?

Live demo

回答2:

Use document.querySelector() if you want to avoid frameworks (which I almost always want to do).

document.querySelector('input[name="gender"]:checked').value

回答3:

In pure Javascript:

var genders = document.getElementsByName("gender");
var selectedGender;

for(var i = 0; i < genders.length; i++) {
   if(genders[i].checked)
       selectedGender = genders[i].value;
 }

update

In pure Javascript without loop, using newer (and potentially not-yet-supported) RadioNodeList :

var form_elements = document.getElementById('my_form').elements;
var selectedGender = form_elements['gender'].value;

The only catch is that RadioNodeList is only returned by the HTMLFormElement.elements or HTMLFieldSetElement.elements property, so you have to have some identifier for the form or fieldset that the radio inputs are wrapped in to grab it first.

回答4:

To get the value you would do this:

document.getElementById("genderf").value;

But to check, whether the radio button is checked or selected:

document.getElementById("genderf").checked;

回答5:

If you wrap your form elements in a form tag with a name attribute you can easily get the value using document.formName.radioGroupName.value.

<form name="myForm">
    <input type="radio" id="genderm" name="gender" value="male" />
    <label for="genderm">Male</label>
    <input type="radio" id="genderf" name="gender" value="female" />
    <label for="genderf">Female</label>
</form>

<script>
    var selected = document.forms.myForm.gender.value;
</script>

回答6:

Try:

var selectedVal;

for( i = 0; i < document.form_name.gender.length; i++ )
{
  if(document.form_name.gender[i].checked)
    selectedVal = document.form_name.gender[i].value; //male or female
    break;
  }
}

回答7:

Without loop:

document.getElementsByName('gender').reduce(function(value, checkable) {
    if(checkable.checked == true) 
        value = checkable.value; 
    return value;
}, '');

reduce is just a function that will feed sequentially array elements to second argument of callback, and previously returned function to value, while for the first run, it will use value of second argument.

The only minus of this approach is that reduce will traverse every element returned by getElementsByName even after it have found selected radio button.

回答8:

function myFunction() {
document.getElementById("text").value='male'
 document.getElementById("myCheck_2").checked = false;
  var checkBox = document.getElementById("myCheck");
  var text = document.getElementById("text");
  if (checkBox.checked == true){
    text.style.display = "block";
  } else {
     text.style.display = "none";
  }
}
function myFunction_2() {
document.getElementById("text").value='female'
 document.getElementById("myCheck").checked = false;
  var checkBox = document.getElementById("myCheck_2");
  var text = document.getElementById("text");
  if (checkBox.checked == true){
    text.style.display = "block";
  } else {
     text.style.display = "none";
  }
}

Male: <input type="checkbox" id="myCheck"  onclick="myFunction()">
Female: <input type="checkbox" id="myCheck_2"  onclick="myFunction_2()">

<input type="text" id="text" placeholder="Name">