Angular 2 - 在数组中查找实例 [英] Angular 2 - find instance in array

问题描述

我正在为一个应用程序构建一个虚拟登录，我需要在一个数组中检查用户登录的实例

Im building a dummy login for an app, and I need to check for an instance of the user logging in, within an array

我有一些模拟数据

import { User } from './user';

export const USERS: User[] = [
  {username: 'Seth', password: 'youwillneverknow'},
  {username: 'Peter', password: 'iforgot'},
  {username: 'Frank', password: 'test123'},
];

我在 user.service 文件中使用的内容

Which I use in my user.service file

import { Injectable } from '@angular/core';
import { User } from './user';
import { USERS } from './users.mock';

@Injectable()
export class UserService {
  getUsers(): Promise<User[]> {
    return Promise.resolve(USERS);
  }

  <some method here>

}

并且在我的组件中，我需要编写一个方法来检查用户是否存在于数组中.

and in my component I need to write a method checking if the user exists in the array.

  logIn(value: string): void {

  }

字符串值来自我的 HTML 中的输入字段

The string value comes from a input field in my HTML

我需要一些关于如何在调用登录函数时检查该用户名的实例的输入

I need some input on how to check for an instance of that username when calling the logIn function

推荐答案

要查找数组的实例，请使用:

To find an instance of an array use:

users.find(x => x.username == value);

这将返回 USER 数组中具有匹配用户名的对象.如果它不存在，它将返回 undefined.

This will return the object in the USER array that with the matching user name. It will return undefined if it doesn't exist.

您也可以使用 findIndex，它将返回数组中与谓词匹配的项目的索引，如果不存在则返回 -1:

You can also use findIndex, which will return the index of the item in the array that matches the predicate or -1 if it doesn't exist:

users.findIndex(x => x.username == value);

至于拥有用户名和密码列表，这绝对不是推荐的身份验证.我希望您正在为生产应用程序做其他事情.

As for having a list of usernames and passwords, this is definitely not recommended authentication. I hope you are doing something else for a production application.

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