CODEWITHSUNDEEP
javascript
beNerd
beNerd

Reputation: 3374

string to number conversion in javascript

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.

Upvotes: 2

Views: 110

Answers (4)

Frederik.L
Frederik.L

Reputation: 5610

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.

Upvotes: 0

tech savy
tech savy

Reputation: 193

try below code

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

Upvotes: -1

Waqar Alamgir
Waqar Alamgir

Reputation: 9968

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));

Upvotes: 0

loganfsmyth
loganfsmyth

Reputation: 161447

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.

Upvotes: 2

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