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

问题描述

我正在为应用构建虚拟登录名，我需要在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文件中使用哪个

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>

}

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

我需要一些有关如何在调用logIn函数时检查该用户名实例的信息

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.

您还可以使用findIndex，它将返回与谓词匹配的数组中该项的索引，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);

关于具有用户名和密码的列表，绝对不建议使用此方法.希望您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.

这篇关于Angular 2-在数组中查找实例的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！