如何检测数组中的相同元素并总结数量？

Question

如何检测MY CART中是否存在所选产品代码，如果产品代码存在，则不要将其插入MY CART数组中，而是将所选产品的数量添加到MY CART中的现有产品中。

我编写的代码会将所有选择的产品添加到我的购物车中，这对于看到所有相同的产品堆积起来并不是很有效。如果产品存在，最好有这个功能来汇总数量。

var cartlist= new Array();
$(".addtocart").on('click', function() {
   var prdcode = $("#prod_code");
   var description = $("#prod_desc");
   var qty= $("#prod_qty");
   var itemlist = new Array();

   itemlist.push(prdcode );
   itemlist.push(description );
   itemlist.push(qty);

   cartlist.push(itemlist);

   for (var i = 0; i < cartlist.length-1; i++) {
      if(cartlist[i+1] === cartlist[i]){
         continue;
         //action to sum qty if code exist in cart 
      }
   }
});

MY CART
0: Array(3){
     0: "ABC123"
     1: "DESCRIPTION FOR ABC123"
     2: "1"
}
1: Array(3){
     0: "DEF456"
     1: "DESCRIPTION FOR DEF456"
     2: "2"
}

TO BE ADDED IN CART
0: Array(3){
     0: "ABC123"
     1: "DESCRIPTION FOR ABC123"
     2: "1"
}
1: Array(3){
     0: "GHI789"
     1: "DESCRIPTION FOR GHI789"
     2: "1"
}

EXPECTED OUTCOME (AFTER ADDED IN CART)
0: Array(3){
     0: "ABC123"
     1: "DESCRIPTION FOR ABC123"
     2: "2"
}
1: Array(3){
     0: "DEF456"
     1: "DESCRIPTION FOR DEF456"
     2: "2"
}
2: Array(3){
     0: "GHI789"
     1: "DESCRIPTION FOR GHI789"
     2: "1"
}

Answer 1

逻辑应该是，在您将商品推送到购物车之前，请检查商品是否已存在于购物车中。如果存在更新它，如果不推送它。

如果你使用for循环，你必须在两个循环中进行

工作代码

var cartlist = new Array();
cartlist.push(["ABC123", "DESCRIPTION FOR ABC123", "1"]);
cartlist.push(["DEF456", "DESCRIPTION FOR DEF456", "2"]);

var itemlist = new Array();
itemlist.push(["ABC123", "DESCRIPTION FOR ABC123", "1"]);
itemlist.push(["GHI789", "DESCRIPTION FOR GHI789", "1"]);

$(".addtocart").on('click', function () {
  // Donot push directly without checking
  // cartlist.push(itemlist);
  for (var i = 0; i < itemlist.length; i++) {
    let isFound = false; 
    for (var j = 0; j < cartlist.length && !isFound; j++) {
      if(cartlist[j][0] === itemlist[i][0] && cartlist[j][1] === itemlist[i][1]) {
        cartlist[j][2] = (+cartlist[j][2] + +itemlist[i][2]).toString();
        isFound = true;
      }
    }
    if(!isFound) {
      cartlist.push(itemlist[i]);
    }
  }
  console.log(cartlist);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<button class="addtocart">Add</button>

您也可以简单地使用 Array.forEach 和 Array.find 来完成。

var cartlist = new Array();
cartlist.push(["ABC123", "DESCRIPTION FOR ABC123", "1"]);
cartlist.push(["DEF456", "DESCRIPTION FOR DEF456", "2"]);

var itemlist = new Array();
itemlist.push(["ABC123", "DESCRIPTION FOR ABC123", "1"]);
itemlist.push(["GHI789", "DESCRIPTION FOR GHI789", "1"]);

$(".addtocart").on('click', function () {
  // Donot push directly without checking
  // cartlist.push(itemlist);
  itemlist.forEach((item) => {
    const itemFromCart = cartlist.find((node) => node[0] === item[0] && node[1] === item[1]);
    if(itemFromCart) {
      itemFromCart[2] = (+itemFromCart[2] + +item[2]).toString();
    } else {
      cartlist.push(item);
    }
  })
  console.log(cartlist)
  
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script> 
<button class="addtocart">Add</button>