如何在不改变容器的情况下更改数组值（对象数组内部）？ javascript

Question

我想要实现的是在这种情况下，当名称为“Mario”时，用 arr 的值填充数组“presents”，我得到的是数组“present”修改，但我想要的是一个非可变数组，只改变空数组的值与另一个数组的值（在这种情况下，我以 arr 为例）

let present= [
    {
      name: "Peter",
      presents: []
    },
    {
      name: "Mario",
      presents: []
    },
    {
      name: "Amanda",
      presents: []
    },
    {
      name: "David",
      presents: []
    }
]
arr = ["car","coal"]

const res= present.map(s =>s.name == "Mario" ? s.presents.concat(arr) : [])

console.log(res)

我想得到什么：

let present= [
    {
      name: "Peter",
      presents: []
    },
    {
      name: "Mario",
      presents: ["car","coal"]
    },
    {
      name: "Amanda",
      presents: []
    },
    {
      name: "David",
      presents: []
    }
]

pd：对不起，我无法解释得更好，还在学习英语。

Answer 1

您可以传播对象并添加所需的数组。

 const present = [{ name: "Peter", presents: [] }, { name: "Mario", presents: [] }, { name: "Amanda", presents: [] }, { name: "David", presents: [] } ], array = ["car", "coal"], result = present.map(({ presents, ...o }) => ({...o, presents: [...presents, ...(o.name === "Mario"? array: [])] })); console.log(result);

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Answer 2

您可以使用 reduce() 执行以下操作，

 const present = [{ name: "Peter", presents: [] }, { name: "Mario", presents: [] }, { name: "Amanda", presents: [] }, { name: "David", presents: [] } ], arr = ["car", "coal"], res = present.reduce((prev, curr) => { if(curr.name === 'Mario') { prev.push({...curr, presents: [...curr.presents, ...arr]}) } else { prev.push(curr); } return prev; }, []); console.log(res);