remove first comma of string from arry

Question

Thanks in advance for your response, I'm checking a ddbb to bring the names of some items and paint them in my ts like this:

app-batch-app-management.ts

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-batch-app-management',
  templateUrl: './batch-app-management.component.html',
  styleUrls: ['./batch-app-management.component.scss']
})

  constructor(private location: Location,
    private activatedRoute: ActivatedRoute,
    private deviceService: DeviceService,
    private appManagementService: AppManagementService) {
    this.deviceNameList = "";
    this.mgmtErrorMessage = null;
    this.deviceId = "";


    this.mgmtErrorMessage = null;

  }

  ngOnInit() {
    this.activatedRoute.queryParams.subscribe(params => {
      this.mgmtErrorMessage = null;
      this.deviceIdList = params["deviceList"];
      this.deviceId = this.deviceIdList[0];


    });
    for (let i = 0; i < this.deviceIdList.length; i++) {
      this.deviceService.getDeviceName(this.deviceIdList[i]).then(deviceName => {
        // if (i === 0) {
        //   this.deviceNameList = deviceName;
        // } else {
        this.deviceNameList += ", " + deviceName;
        // }

      }).catch(err => {
        this.mgmtErrorMessage = "Oops, could not get the device configuration.";
      });
    }
  }

and my app-batch-app-management.html

 <div class="h2 mt-16">Application Management of {{deviceNameList}}</div>

The condition above in my ts, doesn't paint all the items always, I think because of the condition, so I want to remove it, but it's painting a comma in the first place, how could I remove the first comma?

Answer 1

You can just use substring method:

this.deviceNameList = this.deviceNameList.substring(2);

Answer 2

Using Basic regex, you can replace the comma with a blank in the string:

",your,String".replace(/^,/, '')

Note: ^ in regex will get the first Character to remove

Answer 3

Do not use Promise.then inside loops, which will cause undesirable effects (that's why your condition check fails, because it refers to a closure variable). Instead, await it, so your check will work, or alternatively solve the comma problem with join() :

   const names = [];
   for (let i = 0; i < this.deviceIdList.length; i++) {
      try {
         const deviceName = await this.deviceService.getDeviceName(this.deviceIdList[i]);
         names.push(deviceName);
       } catch (err) {
         this.mgmtErrorMessage = "Oops, could not get the device configuration.";
       }
   }
   this.deviceNameList = names.join(', ');