Radio defaultCheckedProperty
Radio Object
Definition and Usage
The defaultChecked property returns the default value of the checked attribute.
If the default state of the radio button is checked, it returns true; otherwise, it returns false.
Syntax
radioObject.defaultChecked
Browser Support
All major browsers support the defaultChecked property.
Example
Example
Detect whether the "Blue" option is selected by default:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Example Tutorial(example.com)</title>
<script>
function displayResult(){
var x=document.getElementById("blue").defaultChecked;
alert(x);
}
</script>
</head>
<body>
<form>
Which color do you prefer?<br>
<input type="radio" name="colors" id="red">Red<br>
<input type="radio" name="colors" id="blue" checked="checked">Blue<br>
<input type="radio" name="colors" id="green">Green
</form>
<button type="button" onclick="displayResult()">Is blue selected by default?</button>
</body>
</html>
<html>
<head>
<meta charset="utf-8">
<title>Example Tutorial(example.com)</title>
<script>
function displayResult(){
var x=document.getElementById("blue").defaultChecked;
alert(x);
}
</script>
</head>
<body>
<form>
Which color do you prefer?<br>
<input type="radio" name="colors" id="red">Red<br>
<input type="radio" name="colors" id="blue" checked="checked">Blue<br>
<input type="radio" name="colors" id="green">Green
</form>
<button type="button" onclick="displayResult()">Is blue selected by default?</button>
</body>
</html>
Try it Yourself »
Radio Object Other Extensions