javascript - 相同的产品但在表中添加另一行(仅限 JavaScript)

Question

我有一个简单的问题。当我将产品添加到购物车并再次将相同的产品添加到购物车时，它会添加另一行。它应该只是增加其数量。希望得到您的答复。这对我来说将是一个很大的帮助。请仅使用纯 JAVASCRIPT。没有 JQUERY。谢谢你们。

    //var qtyTotal = 0;
    //var priceTotal = 0;
    var products = [];


    function addProduct() {
        var productID = document.getElementById("productID").value;
        var product_desc = document.getElementById("product_desc").value;
        var qty = document.getElementById("quantity").value;
        // qtyTotal = qtyTotal + parseInt(qty);
        //document.getElementById("qtyTotals").innerHTML=qtyTotal;
        var price = document.getElementById("price").value;

      var newProduct = {

          product_id : null,
          product_desc : null,
          product_qty : 0,
          product_price : 0.00,
      };
        newProduct.product_id = productID;
        newProduct.product_desc = product_desc;
        newProduct.product_qty = qty;
        newProduct.product_price = price;


        products.push(newProduct);

        //console.log("New Product " + JSON.stringify(newProduct))
        //console.log("Products " + JSON.stringify(products))

        var html = "<table border='1|1' >";
        html+="<td>Product ID</td>";
        html+="<td>Product Description</td>";
        html+="<td>Quantity</td>";
        html+="<td>Price</td>";
        html+="<td>Action</td>";
        for (var i = 0; i < products.length; i++) {
        html+="<tr>";
        html+="<td>"+products[i].product_id+"</td>";
        html+="<td>"+products[i].product_desc+"</td>";
        html+="<td>"+products[i].product_qty+"</td>";
        html+="<td>"+products[i].product_price+"</td>";
        html+="<td><button type='submit' onClick='deleteProduct(\""+products[i].product_id +"\", this);'/>Delete Item</button> &nbsp <button type='submit' onClick='addCart(\""+products[i].product_id +"\", this);'/>Add to Cart</button></td>";
        html+="</tr>";
    }
        html+="</table>";
        document.getElementById("demo").innerHTML = html;

        document.getElementById("resetbtn").click()            
}
    function deleteProduct(product_id, e) {
        e.parentNode.parentNode.parentNode.removeChild(e.parentNode.parentNode);
        for(var i = 0; i < products.length; i++) {
            if (products[i].product_id == product_id) {
                // DO NOT CHANGE THE 1 HERE
               products.splice(i, 1);
            }
        }
    }

    function addCart(product_id){
      var html = '';
      var ele = document.getElementById("demo2");     
      if(ele.innerHTML == '')
      {
        html+="<table id='tblCart' border='1|1'>";
        html+="<tr><td>Product ID</td>";
        html+="<td>Product Description</td>";
        html+="<td>Quantity</td>";
        html+="<td>Price</td>";
        html+="<td>Total</td>";
        html+="<td>Action</td></tr>";
      }
        for (var i = 0; i < products.length; i++) {
            if (products[i].product_id == product_id) {
            products[i].product_qty = parseInt(products[i].product_qty) + 1;
            html+="<tr>";
            html+="<td>"+products[i].product_id+"</td>";
            html+="<td>"+products[i].product_desc+"</td>";
            html+="<td>"+products[i].product_qty+"</td>";
            html+="<td>"+products[i].product_price+"</td>";
            html+="<td>"+parseInt(products[i].product_price)*parseInt(products[i].product_qty)+"</td>";
            html+="<td><button type='submit' onClick='subtractQuantity(\""+products[i].product_id +"\", this);'/>Subtract Quantity</button></td>";
            html+="</tr>";
        }    
    }
      
      if(ele.innerHTML == '')
      {
        html+= "</table>";
        ele.innerHTML = html;
      }
      else
      {
        document.getElementById("tblCart").innerHTML += html;     
      }      
    }
    
    function subtractQuantity(product_id)
    { alert(product_id);
    for(var i = 0; i < products.length; i++) {
        if (products[i].product_id == product_id & products[i].product_qty >= 1) {
            products[i].product_qty = parseInt(products[i].product_qty) - 1;
        }

        if (products[i].product_id == 0) {
            removeItem(products[i].product_id);
        }
        console.log("Products " + JSON.stringify(products));
        
    }
}

function removeItem(product_id) {
    for(var i = 0; i < products.length; i++) {
        if (products[i].product_id == product_id) {
            // DO NOT CHANGE THE 1 HERE
            products.splice(i, 1);
        }
    }
}

<!DOCTYPE html>
<html>
<head>
    <title>Shopping Cart Pure Javascript</title>
</head>
<body>
<form name="order" id="order">
    <table>
        <tr>
            <td>
                <label for="productID">Product ID:</label>
            </td>
            <td>
                <input id="productID" name="product" type="text" size="28" required/>
            </td>
        </tr>
        <tr>
            <td>
                <label for="product">Product Desc:</label>
            </td>
            <td>
                <input id="product_desc" name="product" type="text" size="28" required/>
            </td>
        </tr>
        <tr>
            <td>
                <label for="quantity">Quantity:</label>
            </td>
            <td>
                <input id="quantity" name="quantity" width="196px" required/>
            </td>
        </tr>
        <tr>
            <td>
                <label for="price">Price:</label>
            </td>
            <td>
                <input id="price" name="price" size="28" required/>
            </td>
        </tr>
    </table>
    <input type="reset" name="reset" id="resetbtn" class="resetbtn" value="Reset" />
    <input type="button" id="btnAddProduct" onclick="addProduct();" value="Add New Product" >


</form>
<br>
<p id="demo"></p> <br/>
<h2> Shopping Cart </h2>
<p id="demo2"></p>
</body>
</html>

Answer 1

首先，您尝试将产品和购物车商品存储在SAME ARRAY中。购物车应包含产品实例，而不是相反。

其次，您不断向 html 表格中添加内容，而无需删除前一行(对于同一产品)。

第三，将价格变量转换为整数，货币值应始终为浮点或 double 。

我假设您正在寻找类似以下内容的内容:

var products = [];
        var cart = [];

        function addProduct() {
            var productID = document.getElementById("productID").value;
            var product_desc = document.getElementById("product_desc").value;
            var qty = document.getElementById("quantity").value;
            var price = document.getElementById("price").value;

            var newProduct = {
                product_id: null,
                product_desc: null,
                product_qty: 0,
                product_price: 0.00,
            };
            newProduct.product_id = productID;
            newProduct.product_desc = product_desc;
            newProduct.product_qty = qty;
            newProduct.product_price = price;


            products.push(newProduct);


            var html = "<table border='1|1' >";
            html += "<td>Product ID</td>";
            html += "<td>Product Description</td>";
            html += "<td>Quantity</td>";
            html += "<td>Price</td>";
            html += "<td>Action</td>";
            for (var i = 0; i < products.length; i++) {
                html += "<tr>";
                html += "<td>" + products[i].product_id + "</td>";
                html += "<td>" + products[i].product_desc + "</td>";
                html += "<td>" + products[i].product_qty + "</td>";
                html += "<td>" + products[i].product_price + "</td>";
                html += "<td><button type='submit' onClick='deleteProduct(\"" + products[i].product_id + "\", this);'/>Delete Item</button> &nbsp <button type='submit' onClick='addCart(\"" + products[i].product_id + "\", this);'/>Add to Cart</button></td>";
                html += "</tr>";
            }
            html += "</table>";
            document.getElementById("demo").innerHTML = html;

            document.getElementById("resetbtn").click()
        }
        function deleteProduct(product_id, e) {
            e.parentNode.parentNode.parentNode.removeChild(e.parentNode.parentNode);
            for (var i = 0; i < products.length; i++) {
                if (products[i].product_id == product_id) {
                    // DO NOT CHANGE THE 1 HERE
                    products.splice(i, 1);
                }
            }
        }

        function addCart(product_id) {


            //Indentify the product and add it to new "cart" array
            for (var i = 0; i < products.length; i++) {
                if (products[i].product_id == product_id) {
                    var cartItem = null;
                    for (var k = 0; k < cart.length; k++) {
                        if (cart[k].product.product_id == products[i].product_id) {//Already exists in cart, increment quantity.
                            cartItem = cart[k];
                            cart[k].product_qty++;//Increment by one only, as requested.
                            break;
                        }
                    }
                    if (cartItem == null) {
                        //Every item in the cart specifies the product in question as well as how many of the product there is in the cart, starts off at product's quantity
                        var cartItem = {
                            product: products[i],
                            product_qty: products[i].product_qty // Start of at product's quantity
                        };
                        cart.push(cartItem);
                    }

                    break
                }
            }

            renderCartTable();

        }

        function renderCartTable() {
            var html = '';
            var ele = document.getElementById("demo2");
            ele.innerHTML = ''; //Start by clearng your table of old elements

            html += "<table id='tblCart' border='1|1'>";
            html += "<tr><td>Product ID</td>";
            html += "<td>Product Description</td>";
            html += "<td>Quantity</td>";
            html += "<td>Price</td>";
            html += "<td>Total</td>";
            html += "<td>Action</td></tr>";
            for (var i = 0; i < cart.length; i++) {
                html += "<tr>";
                html += "<td>" + cart[i].product.product_id + "</td>";
                html += "<td>" + cart[i].product.product_desc + "</td>";
                html += "<td>" + cart[i].product_qty + "</td>";
                html += "<td>" + cart[i].product.product_price + "</td>";
                html += "<td>" + parseFloat(cart[i].product.product_price) * parseInt(cart[i].product_qty) + "</td>";
                html += "<td><button type='submit' onClick='subtractQuantity(\"" + cart[i].product.product_id + "\", this);'/>Subtract Quantity</button></td>";
                html += "</tr>";
            }
            html += "</table>";
            ele.innerHTML = html;
        }

        function subtractQuantity(product_id)
        {
            alert("Removing 1 instance of product "+product_id);
            for (var i = 0; i < cart.length; i++) {
                if (cart[i].product.product_id == product_id) {
                    cart[i].product_qty--;//decrement by one
                }

                if (cart[i].product_qty == 0) {
                    cart.splice(i,1);//Remove from cart
                }
                console.log("Products " + JSON.stringify(products));
            }
            //Finally, re-render the cart table
            renderCartTable();
        }

        function removeItem(product_id) {
            for (var i = 0; i < products.length; i++) {
                if (products[i].product_id == product_id) {
                    // DO NOT CHANGE THE 1 HERE
                    products.splice(i, 1);
                }
            }
        }

这将从产品指定的数量开始您的购物车，然后从那里增加/减少 1。