为什么.push()替换JSON数组的最后一个对象

Question

我已经开发了一个Angular4 Basic Crud应用程序，该应用程序与NODEJS后端API进行交互，该应用程序呈现JSON数组的数据。但是，在使用.push((方法将对象添加到JSON数组中时，它将最后一个对象替换为添加的对象，而不是将其推入数组。

以下是员工的定义：

export interface Employee {
id:number,
name:string,
review:string[],
peers:string[]
}

服务方法使HTTP调用如下：

addEmployee(addedEmployee:Employee):Observable<Response>
{
return 
this._http.post("http://localhost:3001/add",addedEmployee)
.pipe(catchError(this.handleError));
}

将员工对象添加到JSON对象数组的后端API代码如下：

app.post('/add',function(req,res){
var addedEmployee={};
addedEmployee.id=req.body.id;
addedEmployee.name=req.body.name;
addedEmployee.review=req.body.review;
addedEmployee.peers=req.body.peers;
employees.push(addedEmployee);
console.log('added');
res.json(employees);
})

前后JSON对象数组的前后，中间和之后，如下：

之前：

employees = [
{
    id: 1,
    name: "John Doe",
    review: ["Hardworking"],
    peers: ["admin", "Matt"]
},
{
    id: 2,
    name: "Matt Hofner",
    review: ["Hardworking"],
    peers: ["admin"]
},
{
    id: 3,
    name: "Judy Ruth",
    review: ["Focused"],
    peers: ["admin", "Matt"]
}
];

中级：

let addedEmployee:Employee = {
  id: 4,
  name: "Trudy",
    review:["Lazy"],
    peers: ["Matt"]
  };

最终：

employees = [
{
    id: 1,
    name: "John Doe",
    review: ["Hardworking"],
    peers: ["admin", "Matt"]
},
{
    id: 2,
    name: "Matt Hofner",
    review: ["Hardworking"],
    peers: ["admin"]
},
{
    id: 4,
    name: "Trudy",
    review: ["Lazy"],
    peers: ["Matt"]
}
];

Answer 1

这很奇怪。这可能不是最好的解决方案，但请尝试.concat((方法：

app.post('/add',function(req,res){
var addedEmployee={};
var singleEmployeeArray = [];
addedEmployee.id=req.body.id;
addedEmployee.name=req.body.name;
addedEmployee.review=req.body.review;
addedEmployee.peers=req.body.peers;
singleEmployeeArray.push(addedEmployee);
employees.concat(singleNewEmployeeArray);
console.log('added');
res.json(employees);
})