<html> 
<body> 
<form> 
<script> 
    function function1() { 
        document.all.myRadioButton1.checked = true; 
    } 
    function function2() { 
        document.all.myRadioButton2.checked = true; 
    } 
    function function3() { 
        document.all.myRadioButton3.checked = true; 
    } 
    function function4() { 
        document.all.myRadioButton4.checked = true; 
    } 
</script> 
<input id="myRadioButton1" type="radio" name="radiobutton" value="radiobutton">VISA 
<input id="myRadioButton2" type="radio" name="radiobutton" value="radiobutton">MASTERCARD 
<input id="myRadioButton3" type="radio" name="radiobutton" value="radiobutton">DISCOVER 
<input id="myRadioButton4" type="radio" name="radiobutton" value="radiobutton">AMERICAN EXPRESS 
<br> 
<input type="button" value="VISA checked" onClick="function1();"> 
<input type="button" value="MASTERCARD checked" onClick="function2();"> 
<input type="button" value="DISCOVER checked" onClick="function3();"> 
<input type="button" value="AMERICAN EXPRESS checked" onClick="function4();"> 
</form> 
</body> 
</html> 
 
     
       
         
     
  
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