If I have multiple checkboxes in a form how can I pass all the checkboxes that are currently checked?

If I have multiple checkboxes in a form how can I pass all the checkboxes
that are currently checked?

This is my code:
<form action="test.php" method="post">
<input type="checkbox" value="value 1"
onClick="updateCards(this.value);">
<input type="checkbox" value="value 2"
onClick="updateCards(this.value);">
<input type="checkbox" value="value 3"
onClick="updateCards(this.value);">
<input type="checkbox" value="value 4"
onClick="updateCards(this.value);">
<input type="checkbox" value="value 5"
onClick="updateCards(this.value);">
</form>
How can I get all the checkboxes that are currently checked?