Previously we have talked about how to access information (element properties) on a form. Below is a form with a text box, a check box, two radio buttons, and a button.

<form name="myForm" method="post">
<input type="Text" name="myText" value=""></input>
<input type="Checkbox" name="myCheck" value="a check"></input>
<input type="Radio" name="myRadio" value="r1"></input>
<input type="Radio" name="myRadio" value="r2"></input>
<input type="Button" name="myButton" value="click me"></input>
<input type="Reset" value="refresh"></input>
<input type="Hidden" name="myHidden" value="stuff"></input>
</form>

To gather information on the form:

• number of elements on the form:
  document.myForm.length  document.myForm.length
  document.myForm.method  document.myForm.method
  
• To get the form name:
  document.forms[0].name  document.forms[0].name
  document.myForm.name  document.myForm.name
  
• To get the text box name:
  document.forms[0].elements[0].name  document.forms[0].elements[0].name
  document.myForm.elements[0].name  document.myForm.elements[0].name
  document.myForm.myText.name  document.myForm.myText.name
  
• To get the text box value:
  document.forms[0].elements[0].value  document.forms[0].elements[0].value
  document.myForm.elements[0].value  document.myForm.elements[0].value
  document.myForm.myText.value  document.myForm.myText.value
  
• To see if a check box has been checked:
  document.forms[0].elements[1].checked  document.forms[0].elements[1].checked
  document.myForm.elements[1].checked  document.myForm.elements[1].checked
  document.myForm.myCheck.checked  document.myForm.myCheck.checked
  get the value of the check box
  document.myForm.myCheck.value  document.myForm.myCheck.value
  
• To see if first radio button has been checked:
  document.forms[0].elements[2].checked  document.forms[0].elements[2].checked
  document.myForm.elements[2].checked  document.myForm.elements[2].checked
  document.myForm.myRadio[0].checked  document.myForm.myRadio[0].checked
  get the value of the first radio button
  document.myForm.myRadio[0].value  document.myForm.myRadio[0].value
  
• Notice the radio buttons are an Array
  To see if second radio button has been checked:
  document.forms[0].elements[3].checked  document.forms[0].elements[3].checked
  document.myForm.elements[3].checked  document.myForm.elements[3].checked
  document.myForm.myRadio[1].checked  document.myForm.myRadio[1].checked
  
• Get the value on the first button :
  document.forms[0].elements[4].value  document.forms[0].elements[4].value
  document.myForm.elements[4].value  document.myForm.elements[4].value
  document.myForm.myButton.value  document.myForm.myButton.value
  
• Get the value on the reset button :
  notice the reset button did not have a name, so use elements[5]
  document.forms[0].elements[5].value  document.forms[0].elements[5].value
  document.myForm.elements[5].value  document.myForm.elements[5].value
  document.myForm.elements[5].type  document.myForm.elements[5].type
  
• Get the value the hidden field :
  document.forms[0].elements[6].value  document.forms[0].elements[6].value
  document.myForm.elements[6].value  document.myForm.elements[6].value
  document.myForm.myHidden.value  document.myForm.myHidden.value
  

Now that we know how to access properties on a form, let's try using this concept to validate whether a user has entered data on a form:
Click here to see the example