vendorPrefix.js

function getPrefix( prop ){	 
	var vendorPrefixes = ['Moz','Webkit','Khtml','O','ms'],  
		style	 = document.createElement('div').style,  
		upper	 = prop.charAt(0).toUpperCase() + prop.slice(1),	
		pref, len = vendorPrefixes.length;	
	while( len-- ){	 
		if((vendorPrefixes[len] + upper) in style){	
			pref = (vendorPrefixes[len]);	 
		}  
	}  
	if(prop in style){	 
		pref = prop;	
	}

        /*exclude additional strings below if output format not an issue*/
	if ( pref ) {
            return '-' + pref.toLowerCase() + '-';
        }

        // fail safe
        return '';		
}

Usage:
console.log(getPrefix('transform'));
console.log(getPrefix('transition'));