Determine whether a variable is set as private or read-only

Consider having a class structure like this:

export class ItemType{

  readonly itemtype_id: number;
  public name :string;

  constructor(itemtype_id: number, name: string) {
    this.itemtype_id = itemtype_id;
    this.name = name;
  }
}

Now, there is a separate component created as an editable label.

<div class="row">
  <div class="col-xs-4">
    <h4><span class="xvrfont padding">{{label}}</span></h4>
  </div>
  <div class="col-xs-2"></div>
  <div class="col-xs-5">

    <div *ngIf="editing">
      <input #editableField
             [required]="required"
             (blur)="onBlur($event)"
             [name]="value"
             [(ngModel)]="value"
             [type]="type"
             [placeholder]="label"
             (keyup.enter)="onEnter()"
             (mouseover)="$event.target.select()"
             />
    </div>
    <div *ngIf="!editing">
      <h4 title="Click to edit" (click)="edit(value);" (focus)="edit(value);" tabindex="0" class="inline-edit">{{value}}&nbsp;</h4>
    </div>


  </div>
</div>

When using this component, the field should be editable based on whether the property is readonly. If the property is readonly, the field should not be editable; otherwise, it should be.

<app-editable-field [isEditable]={{**check if the property is readonly**}} label='Label" [required]="true" type="text"></app-editable-field>

Is there a simple way to determine if a property in a class is readOnly or private?

Answer №1

It's important to remember that Typescript is always compiled into Javascript, so bear that in mind.

All the checks for types, public/private accessibility, and other features that make Typescript great can only be done during compilation. Once you compile it to Javascript, that information is no longer available. This means there's no way to verify if a member is private or readonly at runtime because your browser is running plain Javascript.

If you want to see how your Typescript class is compiled, check out this link: TypeScript Playground

As mentioned by dsfq in the comments, consider using a boolean member to indicate editability of a field.

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