function submitForm() { 
	var message ='';
	saisie=window.document.theform;
	if(saisie.source.value=='') message=message+'Source \n';
	if(saisie.destination.value=='') message=message+'Destination \n';
	if(saisie.vehicule.value=='') message=message+'Vehicule \n';
	if(saisie.trip.value=='') message=message+'Trip type \n';
	if(message != '')
	{
		alert('Please fill the required fields : \n'+message);
		return false;
	} else{
		var content = convertFormDataToPostContent(window.document.theform); 
		doPost('get-price.php', content, 'processResult');
		return true;

	}
}
function processResult(result) { 
document.getElementById('content_area').innerHTML = result; 
}


function doPost(url, content, callback_name) { 
var async_request = false; 
// Mozilla/Safari 
if (window.XMLHttpRequest) { 
async_request = new XMLHttpRequest(); 
async_request.overrideMimeType('text/xml'); 
} // IE 
else if (window.ActiveXObject) { 
async_request = new ActiveXObject("Microsoft.XMLHTTP"); 
} 
async_request.open('POST', url, true); 
async_request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded'); 
async_request.onreadystatechange = function() { 
if (async_request.readyState == 4) { 
response_content = async_request.responseText; eval(callback_name + '(response_content);'); 
 } 
} 
async_request.send(content); 
}

function convertFormDataToPostContent(form_name) { 
var content_to_submit = ''; 
var form_element; 
var last_element_name = ''; 
for (i = 0; i < form_name.elements.length; i++) { 
form_element = form_name.elements[i]; 
switch (form_element.type) { 
// Text fields, hidden form elements 
case 'text': 
case 'hidden': 
case 'password': 
case 'textarea': 
case 'select-one': 
content_to_submit += form_element.name + '='  + escape(form_element.value) + '&'; break; 
// Radio buttons 
case 'radio': if (form_element.checked) { 
content_to_submit += form_element.name + '='  + escape(form_element.value) + '&';
}
break; 
// Checkboxes 
case 'checkbox': if (form_element.checked) {  
if (form_element.name == last_element_name) {  
if (content_to_submit.lastIndexOf('&') ==  content_to_submit.length - 1) { 
content_to_submit = content_to_submit.substr( 0, content_to_submit.length - 1); 
} // Append value as comma-delimited string 
content_to_submit += ',' + escape(form_element.value); 
} else {
content_to_submit += form_element.name + '='  + escape(form_element.value); } content_to_submit += '&'; last_element_name = form_element.name; 
} break; 
}
}  
content_to_submit = content_to_submit.substr(0, content_to_submit.length - 1);
return content_to_submit; 
}