如何增加和减少产品数量？

我想在购物车中增加和减少更多产品数量，并且我希望在span标签中显示当前值。如何增加和减少产品数量？

<a href="javascript:" id="minus2" onclick="decrementValue()"/><strong>-</strong></a> 
<input type="text" id="qty2" name="<?php echo $s?>" min="1" value="<?php echo $quantity; ?>"> 

<a href="javascript:" id="add2" onclick="incrementValue()"/><strong>+</strong></a> 
&nbsp;<a href="cart-item-delete.php?cartdetailsID=<?php echo $cartdetailsID; ?>"><i class="icon-trash icon-large" onclick="return confirm('Do you want to delete cart?');" ></i> </a> 
<?php if($free_qty!=0){ echo "<br>".$free_qty." Free";} ?>

来源

2015-12-10 deena

这里是工作代码增加和减少数量到数量文本框。

<html> 
<body> 

<?php 

    $quantity = 3; 
    $cartdetailsID = 1; 
    $free_qty = 1; 
?> 

<a href="javascript:" id="minus2" onclick="decrementValue()"/><strong>-</strong></a> 
<input type="text" id="qty2" name="<?php echo $s?>" min="1" value="<?php echo $quantity; ?>"> 

<a href="javascript:" id="add2" onclick="incrementValue()"/><strong>+</strong></a> 
&nbsp;<a href="cart-item-delete.php?cartdetailsID=<?php echo $cartdetailsID; ?>"><i class="icon-trash icon-large" onclick="return confirm('Do you want to delete cart?');" ></i> </a> 
<?php if($free_qty!=0){ echo "<br>".$free_qty." Free";} ?> 


<script type="text/javascript"> 

    var qty2 = document.getElementById("qty2"); 
    function decrementValue(){ 

     if(!isNaN(qty2.value) && qty2.value > 0) { 

      qty2.value--; 

     } 

    } 

    function incrementValue(){ 

     if(!isNaN(qty2.value)) { 

      qty2.value++; 

     } 

    } 

</script> 


</body> 
</html>

来源

2015-12-10 11:10:17

如何增加和减少产品数量？

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