title: Using .replace() at a specific index
body: <p>Is there a function that can replace a string within a string once at a specific index? Example:</p>
  
  <pre><code>var string1="my text is my text";
  var string2="my";
  string1.replaceAt(string2,"your",10);
  </code></pre>
  
  <p>and the resultant output would be "my text is your text", Or:</p>
  
  <pre><code>var string1="my text is my text";
  var string2="my";
  string1.replaceAt(string2,"your",0);
  </code></pre>
  
  <p>in which case the result would be "your text is my text". </p>