title: Object.entries with forEach to map array of objects returns undefined except when console.log is used
body: <p>I have an array of objects that have key value pairs, I want to find a specific key in each object and return the value.</p>
  
  <p>A sample of the Array:</p>
  
  <pre><code>filterCounties=[
    {
      "StateName": "Delaware",
      "CountyName": "Kent",
      "FIPS": 10001,
      "Eligibles_2017": 33292,
      "Eligibles_2018": 34938,
      "Penetration_2017": 0.107,
      "Penetration_2018": 0.123
    },
    {
      "StateName": "Delaware",
      "CountyName": "New Castle",
      "FIPS": 10003,
      "Eligibles_2017": 94030,
      "Eligibles_2018": 98080,
      "Penetration_2017": 0.128,
      "Penetration_2018": 0.164
    },
    {
      "StateName": "Delaware",
      "CountyName": "Sussex",
      "FIPS": 10005,
      "Eligibles_2017": 61964,
      "Eligibles_2018": 65990,
      "Penetration_2017": 0.082,
      "Penetration_2018": 0.097
    },
    {
      "StateName": "Delaware",
      "CountyName": "Pending County Designation",
      "FIPS": 10,
      "Eligibles_2017": 9,
      "Eligibles_2018": 0,
      "Penetration_2017": 0,
      "Penetration_2018": 0
    }
  ]
  </code></pre>
  
  <p>The key I am looking for is Penetration_2018 - I can use the following code and output the values using console.log</p>
  
  <pre><code>const mapTest = new Map(
        Object.entries(filterCounties).forEach(([key, value]) =&gt;
          console.log((key, value["Penetration_2018"]))
        )
      );
  </code></pre>
  
  <p>This will output the values: 
  <a href="https://i.stack.imgur.com/6EVPO.png" rel="nofollow noreferrer">console.log output</a></p>
  
  <p>However if I assign to a variable and then log the variable </p>
  
  <pre><code> const mapTest = new Map(
        Object.entries(filterCounties).forEach(
          ([key, value]) =&gt; (key, value["Penetration_2018"])
        )
      );
      console.log(`This is mapTest ${mapTest}`);
  </code></pre>
  
  <p>I get  [object Map] with no values - I thought that when using an arrow function, return was implicit?</p>
  
  <p>Image of output - with or without String concatenation  <a href="https://i.stack.imgur.com/WAHeL.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <p>I ultimately want to extract these values to assign them to the Y axis of a Victory BarChart. Thanks for any insight / guidance.</p>