Increment and decrement qty button on shopping cart page in magento 1.9

Increment and decrement qty button on shopping cart page in magento 1.9

        <div class="qty-wrapper">
            <label for="qty"><?php echo $this->__('Quantity:') ?></label>
            <div class="qty-box">
                 <?php if(!$_product->isGrouped()): ?>
                    <a class="minus" id="<?php echo $_product->getId() . "minus" ?>" href="javascript:void(0);">-</a>
                    <input type="text" readonly="true" name="qty" id="qty<?php echo $_product->getId() ?>" maxlength="12" value="<?php echo ($_product->getStockItem()->getMinSaleQty() ? $_product->getStockItem()->getMinSaleQty() : 1) ?>" />
                    <a class="plus" id="<?php echo $_product->getId() . "plus" ?>"  href="javascript:void(0);">+</a>
                <?php endif; ?>
            </div>
        </div>


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<script type="text/javascript">
$j(document).ready(function() {
    $j(".minus").click(function() {
        var id = this.id;
        var value = $j('#' + id).next('input').val();
        var fieldID = $j(this).next('input').attr("id");
        if (value > 1) {
            value = value - 1;
            $j('#' + fieldID).val(value);
        }
    });
    $j(".plus").click(function() {
        var id = this.id;
        var value = $j('#' + id).prev('input').val();
        var fieldID = $j(this).prev('input').attr("id");
        ++value;
        $j('#' + fieldID).val(value);
    });
});
</script>