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javascript - 如何在不改变容器的情况下更改数组值（对象数组内部）？javascript

问题描述

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：抱歉，我无法解释得更好，仍在学习英语。

标签： javascriptarraysloopsobjectmutation

解决方案

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);
.as-console-wrapper { max-height: 100% !important; top: 0; }

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