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I am currently taking an intro to coding class and we are working with JS. My code is good but I am missing something because for the discount outputs I always get NAN. Does anyone know why this is happening?

//Input
var orderAmount = prompt("What is the order amount?");
var contractor = prompt("Are you a contractor? yes/no?");
var employee = prompt("Are you an employee? yes/no?");
var age = prompt("How old are you?");
//Constant
var employeeDisc = .10;
var largeOrderDisc = .05;
var contractorDisc = .20;
var taxRate = .08;
var noTax = 0;
//Calculations
    if (orderAmount >= 800) {
        var discounta = orderAmount * largeOrderdisc;
    }else {
        var discounta = 0;
    }
    if (contractor == "yes") {
        var discountc = orderAmount * contractorDisc;
    }else if(contractor == "no") {
        var discountc = 0;
    }
    if(employee == "yes") {
        var discounte = orderAmount * employeeDisc;
    }else if(emplyee == "no") {
        var discounte = 0;
    }
var discount = discountc + discounte + discounta;
var subtotal = orderAmount - discount;
    if (age >= 90){
        tax = subtotal * noTax;
    }else {
        tax = subtotal * taxRate;
    }
total = subtotal - tax;
//Output
document.write("Original Price: $" + orderAmount);
document.write("Discount: $" + discount);
document.write("Subtotal: $" + orderAmount);
document.write("Tax: $" + tax);
document.write("Final Price: $" + total);
document.write("Final Price: $" + total);

Sorry about the code not compiling. It is now fixed. The issue now is that my document.write are not writing.

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5 回答 5

2

You are attempting to perform arithmetic calculations and comparisons using strings. NaN is "Not A Number", which is the numeric result of an arithmetic operation that fails (for example dividing by zero, or any calculation on NaN).

Note the use of numbers, not strings, below:

var employeeDisc = .10;
var largeOrderDisc = .05;
var contractorDisc = .20;
var taxRate = .08;
var noTax = 0;
//Calculations
if (orderAmount >= 800) {
    var discounta = orderAmount * largeOrderdisc;
} else {
    var discounta = 0;
}

Additionally, prompt() will return a string. You should convert that to a number before performing your calculations. You probably want to use parseInt() or parseFloat().

Here is a simple example which produces NaN:

var x = 'x5';
var y = '2';
var difference = x - y;
console.log( difference );  // Note: you can use console.log() to write messages to the console in your browser's developer tools.  It is handy for debugging.
于 2013-07-13T15:02:49.940 回答
1

While you really should use numeric variables, JavaScript will convert the values as needed. I tested your code and the real problem with it is these two lines:

}else (contractor == "no") {

and

}else (emplyee == "no") {

These should be

}else if(contractor == "no") {

and

}else if(emplyee == "no") {

The script won't even compile as posted, so I don't know how you're even getting NaN.

于 2013-07-13T15:16:35.963 回答
1

Your else statements are now improper so the code won't run at all. Remove the expressions like (contractor == "no") Here is a fiddle to show it working. http://jsfiddle.net/bitfiddler/6fYvd/

于 2013-07-13T15:25:43.123 回答
0

In Javascript NaN(Not a Number) is returned whenever you try to do mathematical operation on data which is not a number. You will need to check at which step it is returning string instead of number

于 2013-07-13T15:04:08.500 回答
0

It's because you declare your discount variables in if clauses. Define them outside of if clauses, then you will have no problem.

var discounta;
if (a > b) {
   discounta = 0.1;
}
else {
   discounta = 0.2;
}

Also check variable scopes for javascript.

于 2013-07-13T15:04:23.970 回答