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Angular 5 Constant

Angular 5 Constant and Global Variables


How to CREATE constant in your Angular 5 Apps? A constant is a value that can’t be changed by the program during normal execution.
                                                                 OR
Constants are of fixed values that do not change during the execution of a program. There are various types of constants. The Constant types are – Numeric, Character, Integer and many more.

And constant class looks like –
export class AppConstants {
    public static get baseURL(): string { return "http://localhost:4200/api"; }
}

And Use of constant in Services –
import { Injectable } from '@angular/core';
import {HttpClient, HttpParams, HttpHeaders} from "@angular/common/http";
import { Employee } from './employee';
import{ AppConstants} from '../app/constants'

@Injectable()
export class EmployeeService {
 
  //variable initialization
  headers : any;
  _baseURL : string;

  //constructor initialization
  constructor(private _htc:HttpClient) {
      this.headers = new HttpHeaders().set('content-type', 'application/json');
      this._baseURL = AppConstants.baseURL;
  }

  // POST employee - for creating a New employee.
  addEmployee(emp :any){
    var employee = {
        name:emp.name,
        Dep:emp.Dep,
        Des:emp.Des 
    } 
    return this._htc.post<Employee>(this._baseURL+'/Employees/Add', employee, (this.headers));
  }

  //DELETE employee - for delete employee.
  deleteEmployee(id :string){    
    return this._htc.delete<Employee>(this._baseURL+'/Employees/Delete/'+id);
  }
}

ANIL SINGH

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