window.onload = function()
{
	setInterval("check_form()",500);
}

function check_form(){
	var file_name = document.getElementById("file_name").value;

	var image_check = file_name.match(/jpg|png|jpeg/gi);


	if(file_name == "" || image_check == null){
		document.getElementById("send_button").disabled = true;
		document.getElementById("check_image").innerHTML = '<font color="#FF0000">拡張子がJPEGかPNGの画像を選択してください。</font>';
	}else{
		document.getElementById("send_button").disabled = false;
		document.getElementById("check_image").innerHTML = "";
	}
}