How to check to make sure a radio button is selected
I have a form that I need to figure out the code on how to make sure a radio button is selected
Here is the form
<body>
<div id="content">
<p>Enter the values below and click "Calculate".</p>
<label for="length">Length:</label>
<input type="text" id="length" /><br />
<label for="width">Width:</label>
<input type="text" id="width" /><br />
<label for="answer">Answer:</label>
<input type="text" id="Answer" disabled="disabled" /><br />
<input type="radio" name="Area" value="Area" check="checked"/>Area<br />
<input type="radio" name="Parimeter" value="Parimeter" />Parimeter<br />
<label> </label开发者_StackOverflow中文版>
<input type="button" id="calculate" value="Calculate" /><br />
</div>
</body>
</html>
here is the code
var $ = function (id) {
return document.getElementById(id);
}
var calculate_click = function () {
var length = parseFloat( $("length").value );
var width = parseFloat( $("width").value );
// $("area").value = "";
if (isNaN(length) || length <= 0) {
alert("Length must be a valid number\nand greater than zero.");
} else if(isNaN(width) || width <= 0) {
alert("Width must be a valid number\nand greater than zero.");
}
} else {
var area = width * length;
var perimeter = 2 * width + 2 * length;
$("area").value = area.toFixed(2);
$("perimeter").value = perimeter.toFixed(2);
}
}
window.onload = function () {
$("calculate").onclick = calculate_click;
$("length").focus();
}
Here are some links that may help you finish your homework:
- http://www.w3schools.com/html/html_forms.asp
- http://www.w3schools.com/jquery/default.asp
- http://jsfiddle.net
加载中,请稍侯......
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