Disable Button Until Text Field Is Fill

Disable Button Until Text Field Is Fill !

$(function() {
	
	$("#fullName").blur(function(){
		if($(this).val() != ""){
			$("#required_fullName").css("color", "green");
			if($("#emailAddress").val() != '' && $("#phoneNumber").val() != ''){
				$("#PaymentSwitch").attr("disabled", false);
			} else {
				$("#PaymentSwitch").attr("disabled", true);
			}
		} else {
			$("#required_fullName").css("display", "block");
			$("#required_emailAddress").css("display", "block");
			$("#required_phoneNumber").css("display", "block");
			$("#PaymentSwitch").attr("disabled", true);
		}
	});
	$("#phoneNumber").blur(function(){
		if($(this).val() != ""){
			$("#required_phoneNumber").css("color", "green");
			if($("#emailAddress").val() != '' && $("#fullName").val() != ''){
				$("#PaymentSwitch").attr("disabled", false);
			} else {
				$("#PaymentSwitch").attr("disabled", true);
			}
		} else {
			$("#required_fullName").css("display", "block");
			$("#required_emailAddress").css("display", "block");
			$("#required_phoneNumber").css("display", "block");
			$("#PaymentSwitch").attr("disabled", true);
		}
	});
	$("#emailAddress").blur(function(){
		if($(this).val() != ""){
			$("#required_emailAddress").css("color", "green");
			if($("#phoneNumber").val() != '' && $("#fullName").val() != ''){
				$("#PaymentSwitch").attr("disabled", false);
			} else {
				$("#PaymentSwitch").attr("disabled", true);
			}
		} else {
			$("#required_fullName").css("display", "block");
			$("#required_emailAddress").css("display", "block");
			$("#required_phoneNumber").css("display", "block");
			$("#PaymentSwitch").attr("disabled", true);
		}
	});
	
	$("#PaymentSwitch").change(function() {
		var check = document.getElementById("PaymentSwitch");
		if(check.checked == true) {
			if($("#fullName").val() != '' && $("#emailAddress").val() != '' && $("#phoneNumber").val() != ''){
				$("#PaymentSubmit").attr("disabled", false);
			}
		} else {
			$("#PaymentSubmit").attr("disabled", true);
		}
	});
	
});