function validateLogin(f){

	if(f.username.value == ""){
		alert("Please enter your username")
		f.username.focus()
		return false;
	}
	if(f.password.value == ""){
		alert("Please enter your password")
		f.password.focus()
		return false;
	}
	return true;

}

function adjustQty(el, method) {
	if(checkQty(el.value)){
		if (method=="increase") {
			el.value++; 
		}
		else if (method=="decrease"){
			if(el.value>0){
				el.value--; 
			}
		}
	} else {
		el.value="1"; 
		el.focus(); 
	}
}

function checkQty(v) { 
	if ((!validQty(v))||(v<0)) { 
		alert('You have entered an invalid quantity!'); 
		return false
	} else {
		return true
	}
} 

function validQty(v) { 
    	if (isNaN(v.replace(/ /g,""))) {
    		return false;
    	}
    	else return true;
}