How does JavaScript get the value of input type = "radio?

< Script Language = " Javascript " >
<! --
Function Chk () {
VaR OBJ = Document. getelementsbyname ( ' Imgposition ' );
For (I = 0 ; I < OBJ. length; I ++ ) {
If(OBJ [I]. Checked){
Alert (OBJ [I]. value );
Return;
}
}
Alert ( ' You did not select ' );
}
// -->
< / SCRIPT>
< Form name = Form1 >
< Input type = " Radio " Name = " Imgposition " Value = " 1 " >
< Input type = " Radio " Name = " Imgposition " Value = " 2 " >
< Input type = " Radio " Name = " Imgposition " Value = " 3 " >
< / Form>
< Input type = " Button " Onclick = " Chk () " >

For Example:


< Input type = Radio name = " Radio " Checked > 1 - 10 Years Old
< Input type = Radio name = " Radio " > 11 Years Old
< Input type = Radio name = " Radio " > 12 - 120 Years Old
This example uses script to detect which radio button the user selects.

< Script >
Function Detect ()
{
If (Radio [ 0 ]. Checked)
Alert ( " You're between 1 and 10 years old. " )
Else   If (Radio [ 1 ]. Checked)
Alert ( " You're 11 years old. " )
Else
Alert ( " You're between 12 and 120 years old. " )
}
< / SCRIPT>