Javascript：forEach中的错误

Question

我试图执行一个简单的forEach循环。

if (this.list.length == 0) {
    this.list.push({ name, price, familly, quantity })
} else {
    this.list_achat.forEach((element) => {
        if (element.name === name && element.familly === familly) {
            element.quantity += quantity
        } else {
            this.list.push({ name, price, familly, quantity })
        }
        this.prix_totale += element.quantity * element.price
    })
}

当我首先添加一个产品以在list_achat.length == 0时添加list_achat，但是当我添加另一个产品时会发生什么

[
  {"name":"prod1","price":"10","familly":"famille1","quantity":"4"},
  {"name":"prod2","price":"10","familly":"famille1","quantity":"3"},
  {"name":"prod2","price":"10","familly":"famille1","quantity":"2"},
  {"name":"prod2","price":"10","familly":"famille1","quantity":1}
]

我想只保留

[
  {"name":"prod1","price":"10","familly":"famille1","quantity":"4"},
  {"name":"prod2","price":"10","familly":"famille1","quantity":"3"}
]

可能是什么问题？

Answer 1

您每次调用forEach回调时都会添加数组（适用于每个元素）。

你可能正在寻找Array.prototype.find，它会返回数组中第一个回调一个真值的元素（如果没有找到undefined）：

const entry = this.list.find(e => e.name == name && e.familly == familly);
if (!entry) {
    this.list.push({name,price,familly,quantity})
} else {
    entry.quantity +=  quantity;
}