Javascript 校验页面内容后，页面还是会提交？？
代码如下：

function   submit1_onclick()   {

var   str   =   document.getElementById( 'hObligatory ').value;

if   (str   ==   " "   ){
alert( "please   select   accessories¡£ ");
document.getElementById( 'hObligatory ').focus();
return     false;      
}  

return   window.confirm( "Are   you   sure? ");
}

<INPUT   class= "button "   id= "Submit1 "   type= "submit "   value= "Add   to   Shopping   Cart "   name= "ButtonSubmit ">

每次单击button都会弹出提示窗口，但点击提示窗口的‘确定’后页面还是会触发提交事件，请教高手，这是为什么？？
onclick= "return   submit1_onclick() ">

------解决方案--------------------
<INPUT class= "button " id= "Submit1 " type= "submit " value= "Add to Shopping Cart " name= "ButtonSubmit ">

把这里的type= "submit " 改成type= "button "