HTML: JavaScript: Block Form submission and call Javascript function

Add the onsubmit attribute to the form tag:

<form name="search" onsubmit="return makeSearch()" >
  Name: <input type="text" name="name1"/>
  Age: <input type="text" name="age1"/>
  <input type="submit" name="Submit" value="Submit"/>
</form>

And javascript add return false at the end:

function makeSearch() {
  alert("Code to make AJAX Call");
  return false;
}