创建一个处理Javascript中的对象数组的函数

Question

所以我有一个对象数组，看起来像：

list = [firstObject {name: 'a', price: 0.5, quantity: 5, total: 2.5},
        secondObject {name: 'b', price: 2, quantity: 2, total: 4},
        thirdObject {name: 'd', price: 2, quantity: 1, total: 2}]

我正在尝试编写一个函数，使我可以打印类似

• 5 a的费用为$ 2.5
• 2 b的费用为$ 4

• 1 c花费$ 2

• 总计$ 8.50

到目前为止，我有类似

let summary = (name, quantity, total) => {
 let item = list.name;
 let amount = list.quantity;
 let cost = list.total;
  return (`${amount} ${item} costs ${cost}`);
};

但这显然行不通。 我想我对如何使用我的函数正确访问那些对象中的值有些困惑。 任何投入将不胜感激！

Answer 1

你想做这样的事情

list = [{name: 'a', price: 0.5, quantity: 5, total: 2.5},
        {name: 'b', price: 2, quantity: 2, total: 4},
        {name: 'd', price: 2, quantity: 1, total: 2}];

function sum(list){
   let total = 0;

   list.forEach((item)=>{
      console.log(item.quantity + ' ' + item.name + ' costs ' + (item.price * item.quantity));
       total += item.price * item.quantity;
   }
   return total;
});
console.log('Total: ' + sum(list));

Answer 2

试试这个片段

<script>
let summary = (name, quantity, total) => {
    let item = name;
    let amount = quantity;
    let cost = total;
    return (`${amount} ${item} costs ${cost}`);
};
var list = [firstObject = {name: 'a', price: 0.5, quantity: 5, total: 2.5},
           secondObject = {name: 'b', price: 2, quantity: 2, total: 4},
           thirdObject = {name: 'd', price: 2, quantity: 1, total: 2}];

for (var item = 0; item < list.length; item++) {
    summary(list[item].name, list[item].quantity, list[item].total);
}
</script>

Answer 3

可以使您的函数工作以返回一个条目的字符串，而不返回list的字符串，因此您应该更改该变量引用。 您可以在function参数中使用解构，因此不需要任何其他变量或属性引用。

然后，您需要为list每个元素调用该函数。 您可以使用map此操作，这将为您提供字符串数组。 最后，将该数组连接到一个字符串中：

 const list = [{name: 'a', price: 0.5, quantity: 5, total: 2.5}, {name: 'b', price: 2, quantity: 2, total: 4}, {name: 'd', price: 2, quantity: 1, total: 2}]; const summary = ({name, quantity, total}) => `${quantity} ${name}'s cost $${total}`; const output = list.map(summary).join('\\n'); console.log(output); // Code to display the total: const total = list.reduce((sum, {total}) => sum + total, 0); console.log(`The total is $${total}`); 

Answer 4

list = [{name: 'a', price: 0.5, quantity: 5, total: 2.5},
    {name: 'b', price: 2, quantity: 2, total: 4},
    {name: 'd', price: 2, quantity: 1, total: 2}]

function display (obj) {
    console.log(obj.quantity + " " + obj.name +  "'s costs $" + obj.total);
};

let total = 0;
list.forEach(function(obj) {
    display(obj);
    total += obj.total;
});

console.log("The total was ", total);

Answer 5

这是经典

（您首先需要在此处修复对象声明的数组...）

list = 
[
   { name: 'a', price: 0.5, quantity: 5, total: 2.5 },
   { name: 'b', price: 2, quantity: 2, total: 4 },
   { name: 'c', price: 2, quantity: 1, total: 2 }
];

然后您可以继续执行任务

var total = 0;
 for( var item in list )console.log(
       list[ item ].quantity + " " + list[ item ].name + "\'s cost $" + list[item].total
    ), total += list[ item ].total;
console.log( "The total was $"+ total );