string to number conversion in javascript

Question

I have a function having following lines:

payementReceived=data.toJSON().total;
paymentTotal=$("#paymentTotal").html();

console.log(typeof(parseInt(paymentTotal)));                  
console.log(typeof(parseInt(paymentReceived)));
console.log(parseInt(paymentTotal)-parseInt(paymentReceived));

I get the following in console

number
number
NaN

i don't understand if both are numbers then why it isn't able to give the proper substraction result.

new Number(), not just Number(). Or rather - parseInt(xxx, 10) — Oded
– Oded, Commented May 16, 2013 at 7:40
What are the values of paymentTotal and paymentReceived? — Oded
– Oded, Commented May 16, 2013 at 7:41
Note that when you use parseInt, you should always include 10 as a second parameter (otherwise numbers starting with a 0 will be read as base 8!) — Basic
– Basic, Commented May 16, 2013 at 7:44

loganfsmyth · Accepted Answer · 2013-05-16 07:41:41Z

2

The values are number in that their contents are a number, but it doesn't mean that the number is valid.

typeof NaN === 'number'

If you are getting a NaN back from your subtraction, one or both of your input values are invalid numbers.

answered May 16, 2013 at 7:41

loganfsmyth

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Comments

Waqar Alamgir · Accepted Answer · 2013-05-16 08:05:22Z

0

problem is because of the undefined varaible used "paymentReceived" if you are sure that the result is a number you can always use parseInt

console.log(parseInt(paymentTotal)-parseInt(payementReceived));

answered May 16, 2013 at 8:05

Waqar Alamgir

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Frederik.L · Accepted Answer · 2013-05-16 08:47:51Z

0

Just a funny idea :

if (typeof n === "number" && n+1 !== n) {
    // this is a valid number
}

invalid+1 will still be invalid so it could check for invalid numbers.

edited May 16, 2013 at 8:47

answered May 16, 2013 at 8:42

Frederik.L

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Comments

tech savy · Accepted Answer · 2013-05-16 08:39:02Z

-1

try below code

console.log(Number(paymentTotal)-Number(payementReceived));

answered May 16, 2013 at 8:39

tech savy

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