html form submit without refresh code example

Example 1: how to make form not reload page

<form onsubmit="return false">
</form>

Example 2: submit form without page refresh using ajax jquery and php

$(document).ready(function(){
		$('button').click(function(event){
			event.preventDefault();
			var	name = $('#name').val();
			var	mobile = $('#mobile').val();
			var	address = $('#address').val();
			var	city = $('#city').val();
			$.ajax({
			    type: "POST",
			    url: "upload.php",
			    data: { name:name, mobile:mobile, address:address, city:city },		    
			    dataType: "json",
			    success: function(result){
			        			    }
			});
		});
	});

Example 3: why does my page reloads on form submission

//jquery method //
//preventDefault() prevents the submit button
//from performing its default task like page reload  
  $('#form').submit(function (e) {
      e.preventDefault();
  });

Example 4: make submit button not refresh page

If possible, change it to a normal button