javascript单选按钮验证

Question

hey guys i just try to do some validate for my javascript radio button, but is not work. every time i click submit button it just nothing happened.below is the code.


HTML part

   <form name="FirstPizza">
         <td>
             Style:
                <br/>
            <input type="radio" name="style"/>
            Thin Crust
                <br />
            <input type="radio" name="style" />
            Deep Dish
                <br />
            <input type="radio" name="style" />
            Sicilian
        </td>
   </form>

Javascript:

function submitForm(){
        if((!form.style[0].checked)  && (!form.style[1].checked) && (!form.style[2].checked))
             {
           window.alert("You must have a  style")
             }

i should come with a box but nothing happen. Do i miss something?

Answer 1

You were close! According to your comment, your form variable was not defined. You need to define form somewhere like this:

function submitForm() {
  // define the form variable
  var form = document.getElementsByName("FirstPizza")[0];

  if((!form.style[0].checked)  && (!form.style[1].checked) && (!form.style[2].checked))  {
    window.alert("You must have a style");
  } else {
    window.alert("a style was selected");      
  }
}

(see working jsfiddle here )

Answer 2

Use IDs for your form controls! Try this:

HTML part

   <form name="FirstPizza">
         <td>
             Style:
                <br/>
            <input type="radio" id="rbThinCrust" name="style"/>
            Thin Crust
                <br />
            <input type="radio" id="rbDeepDish" name="style" />
            Deep Dish
                <br />
            <input type="radio" id="rbSicilian" name="style" />
            Sicilian
        </td>
   </form>

Javascript:

function submitForm(){
        if (!document.getElementById("rbThinCrust").checked && !document.getElementById("rbThinCrust").checked && !document.getElementById("rbThinCrust").checked)
           //Logic for nothing being checked
}

Answer 3

Both your HTML and JavaScript are completely broken.

First, your HTML. You have no HTML for a button there, which you need should you wire your javascript event to it in the first place.

You would create a submit button like this:

<input type="submit" value="Submit" onclick="submitForm(this)" />

Your radio buttons also should have their text set via the value attribute, like so:

<input type="radio" name="style" value="Thin Crust" />
<input type="radio" name="style" value="Deep Dish" />
<input type="radio" name="style" value="Sicilian" />

Now your javascript, it should look something more like this:

function submitForm(form){
    if((!form.style[0].checked)  && (!form.style[1].checked) && (!form.style[2].checked))
    {
        window.alert("You must have a  style")
}

Hope that works for you.

And your end HTML should look like this:

<form name="FirstPizza">
Style:<br />
<input type="radio" name="style" value="Thin Crust" />Thin Crust<br />
<input type="radio" name="style" value="Deep Dish" />Deep Dish<br />
<input type="radio" name="style" value="Sicilian" />Sicilian
</form>