Question

我有一个数组

let arr = []

我正在向其中插入对象

let a = {name:"a", age: 20}
arr.push(a);

我正在检查以下具有相同对象分配给不同变量的索引

let b = {name:"a", age:20}

我尝试了

arr.indexOf(b);

我得到-1，我期望为0。

请指导我

Answer 1

JS按引用而不是按值进行对象比较（和搜索）。因此：要使foo == bar为真，foo和bar必须是同一对象，而不仅仅是具有相同属性和值的对象：

console.log({name:"a", age:20} == {name:"a", age:20});

因此，您需要使用诸如findIndex之类的东西，而不是indexOf。

let arr = [];
let a = {name:"a", age: 20};
arr.push(a);
let b = {name:"a", age:20}

const index = arr.findIndex(item => item.name === b.name && item.age === b.age);
console.log(index);

Answer 2

这是因为对象是引用类型，变量a和b指向两个不同的存储位置。因此a != b

let a = {name:"a", age: 20};
let b = {name:"a", age:20}
console.log(a == b);

Answer 3

JavaScript默认情况下无法比较对象。请改用Array.findIndex：

let arr = []

let a = {name:"a", age: 20}

arr.push(a);
let b = {name:"a", age:20}


console.log(arr.findIndex(elem => elem.name == b.name && elem.age == b.age));

Answer 4

是的，因为Js通过使用引用而不是按值进行比较

let arr = [];

let a = {
  name: "a",
  age: 20
};
arr.push(a);

let b = {
  name: "a",
  age: 20
};

console.log(arr.indexOf(b));

let arr = [];

let a = {
  name: "a",
  age: 20
};
arr.push(a);

let b = a

console.log(arr.indexOf(b));

对象索引未达到预期的数组

4 个答案: