title: Check if properties of a TypeScript object are all empty
body: <p>I have an object that looks like this:</p>
  
  <pre><code>objectProp = {
    property1: [],
    property2: [],
  }
  </code></pre>
  
  <p>I want to check if all properties(that are string arrays) if this object are null and return true.
  I am for some reason stuck. How can I do this?
  I am using "target": "es2015" </p>
  
  <p>I tried this but does not work:</p>
  
  <pre><code> if (!Object.keys(this.objectProp).every(array =&gt; array.length &gt; 0)) {
        console.log('all are empety');
      }
  </code></pre>