'Why form is not submtinig after adding two javascript function

When i add two function in form everything goes okay but nothing submitted like value=1 or value=2

<form method="get" name="formSubmit" onsubmit="return !!(download() & brojac());">
                 <input type="checkbox" name="formWheelchair" value="1" />Razglednica 1<br>
                 </td>
                 <td align="center">
                 <input type="checkbox" name="formWheelchair" value="2" />Razglednica 2<br>
                 </td>
                 <td align="center">
                 <input type="checkbox" name="formWheelchair" value="3"  />Razglednica 3<br>
                 </td>
                 <div align="center">
                <input type="submit" class="button" name="formSubmit" value=" E-MAIL SA SELFIEM" />
                 </form>


Solution 1:[1]

make third function and put both function in it. and then onsubmit call that third function. put your javascript file for more briefly explanation.

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Source: Stack Overflow

Solution Source
Solution 1 yashil shah