title: How to make a character/special character mandatory in a string using Regex
body: <p><strong>Requirement</strong>: String should have one or more . (dot) in middle of the string.</p>
  
  <p><strong>Example</strong> : </p>
  
  <pre><code>      "abccom"      false
        ".abc.com"    false
        "abccom."     false
        "abc:.com"    false
        "abc..com"    false
  
        "a2b.com"     true
        "abc.com"     true
        "ab.cc.in"    true
  </code></pre>
  
  <p><strong>Tried</strong>: </p>
  
  <pre><code>var regex = /^[a-z0-9]+(.[a-z]+)?$/;
  regex.test("abccom")  // Output : true
  </code></pre>
  
  <p>Explain a bit about how to make a particular character mandatory or relevant link.</p>