返回类型打字稿函数中的问题

Question

i have a simple fonction in my typescript fonction which returns a number:

import { Input } from '@angular/core';
export class UsersService {
  currentusers = [
    {
      name: 'kanzari zied',
      age: 29
    },
    {
      name: 'ahmed mastouri',
      age: 32
    },
    {
      name: 'samir bargaoui',
      age: 40
    }
  ];
  getUserByName(nom: string) :number {     
    this.currentusers.forEach( (item, index) => {
        if(item.name == nom) {
            console.log("its found"+item.age);
            return item.age;
        }
      });
      return 0;
}

}

and here is my component which should show the age :

import { Component, OnInit, Input } from '@angular/core';
import { UsersService } from '../services/users.service';
import { ActivatedRoute } from '@angular/router';

@Component({
selector: 'app-single-user',
templateUrl: './single-user.component.html',
styleUrls: ['./single-user.component.scss']
})
export class SingleUserComponent implements OnInit {
@Input() nom:string;
@Input() age:number;
constructor(private UsersService:UsersService,private route: 
ActivatedRoute) { }
ngOnInit() {
this.nom = this.route.snapshot.params['nom'];
console.log("---------"+this.nom);
this.age=this.UsersService.getUserByName(this.nom);   
console.log("current age "+this.age);
  }

  }

Problem is : in the service i can see the age when i console.log it , but in the component.ts it returns 0 !!!! please i dont understand why

Answer 1

forEach doesn't have a return value. You need to do something like this:

  getUserByName(nom: string) :number { 
    const age = 0;    
    this.currentusers.forEach( (item, index) => {
        if(item.name == nom && !age) {
            console.log("its found"+item.age);
            age = item.age;
        }
      });
      return age;
}

Answer 2

You should be using find method:

function getUserByName(nom: string): number {
    const user = this.currentusers.find(user => {
        return user.name === nom;
    });
    return user ? user.age : 0;
}

Answer 3

The return statement you wrote ie return item.age; is for the callback function of forEach, not for the getUserByName function. You need to return the age in getUserByName . Also, find is more suitable method here as in case of forEach, you cannot exit once value is found.

  getUserByName(nom: string) :number {     
    const result=this.currentusers.find( (item) => {
        return (item.name == nom);
      });
    if(result){
       return result.age
     }
    return 0;
}

Answer 4

Find is a good method, and it can be used simpler:

function getUserByName(nom: string): number {

    const user = this.currentusers.find(a => a.name === nom);
    if(user){
        console.log("its found"+user.age);
     return user.age ;
     }
   return 0;      
}