Don't send form data when to type no in confirm window

Type apple in the input whose name is goods,and type 9 in the input whose name is price,and click submit,now confirm window pop up,whatever your click yes or no,the data will send to price.php.
My expectation:
when you click yes ,the data will send to price.php, when you click no ,the data will not send to price.php,what's wrong for my js?

ob = document.getElementById("submit");
function check(){
    if(document.getElementById("price").value < 10){
        var flag = window.confirm(" are your sure the price is less than 10 ?");
        if(flag){
            return true;
        }else{
            exit;
         }
    }
}
ob.addEventListener("click",check,false); 
 

<form action="price.php" method="post">
<table>
    <tr>
        <td>goods</td>
        <td><input type="text" name="goods"></td>
    </tr>
    <tr>
        <td>price</td>
        <td><input type="text" id="price" name="price"></td>
    </tr>
    <tr><td colspan=2><input type="submit" id="submit"  value="submit"></td></tr>
</table>
</form> 
 

The price.php is simple.

<?php
var_dump($_POST);
?>

The exit below can't prevent form data from sending to price.php.

        if(flag){
            return true;
        }else{
            exit;
         }  

It is no use either to change exit; into return false;. It is no use either to change js into below.

ob = document.getElementsByTagName("submit")[0];
function check(){
    if(document.getElementById("price").value < 10){
        var flag = window.confirm(" are your sure the price is less than 10 ?");
        if(flag){
            return true;
        }else{
            exit;
         }
    }
}
ob.addEventListener("submit",check,false); 

from Don't send form data when to type no in confirm window