title: I want to replace last comma with "and " in a string using javascript
body: <p>I want to replace last comma in a string with and...
  for eg </p>
  
  <pre><code>var ambassadorName = test, test, test
  </code></pre>
  
  <p>the output must be </p>
  
  <pre><code>var ambassadorName= test, test and test. 
  </code></pre>
  
  <p>Please help me with the code</p>