title: How to get Length from Array Model in Typescript
body: <p>I am trying to get the length from Array interface. But getting error as:</p>
  
  <p><code>error TS2339: Property 'length' does not exist on type 'ModelSubSystems'.</code> In this case how to get the length. here is my TS code:</p>
  
  <pre><code>@Input() subsystems: ModelSubSystems;
  
  resolve({ data: this.subsystems, totalCount: this.subsystems.length }); //error
  </code></pre>
  
  <p>here is my interfaces:</p>
  
  <pre><code>export interface ModelSubSystem {
      Id: number;
      Name: string;
      CreatedBy: string;
      CreatedDate: Date;
      UpdatedBy: string;
      UpdatedDate: Date;
  }
  
  export interface ModelSubSystems {
      subsystems: Array&lt;ModelSubSystem&gt;; //this is array!!
  }
  </code></pre>
  
  <p>any one help me with correct approach.
  Thanks in advance.</p>