javascript how to set null input equal to 0

Question

I have javascript function that will calculate the value for "TOTAL" row and "Balance" column in the table. But if there are no input, the javascript will return NaN which is not a number error. How to set if there are no input in the text box, javascript will interpret it as 0 so that I will not get NaN error.

As you can see, the textbox for pay(notes 50) column are empty. Then value for balance and total become NaN.

I guess you are probably using parseInt or equivalent somewhere. Just add an if statement to check if the String is equal to "" or not (empty string) — user2345
– user2345, Commented Dec 1, 2016 at 7:17
You can use isNan() function for checking it or you should convert the inputs to integer using parseInt(). — Quicksilver
– Quicksilver, Commented Dec 1, 2016 at 7:17
Or change to something like parseInt(value || 0) so that it defaults to 0 if value is not a number. — user2345
– user2345, Commented Dec 1, 2016 at 7:18
@nicovank, I've tried parseInt(value || 0) when declaring the variable and managed to parsed the value to int and set to 0 if null. Thank you so much. — 8man
– 8man, Commented Dec 1, 2016 at 8:56

A.T. · Accepted Answer · 2016-12-01 07:23:42Z

1

just use logical 'or' operator (see short-circuit evaluation),

parseInt('10') || 0; // give 10
parseInt('') || 0; // give 0

answered Dec 1, 2016 at 7:23

A.T.

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Comments

Chiu · Accepted Answer · 2016-12-01 07:18:05Z

0

You can check whether the value is a number by isNaN() function and then perform summation.

answered Dec 1, 2016 at 7:18

Chiu

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Grey · Accepted Answer · 2016-12-01 07:31:25Z

0

use isNaN(), put it in an if statement, if true, set the variable to 0

if(isNaN(yourVar)) {
    yourVar = 0;
}

edited Dec 1, 2016 at 7:31

answered Dec 1, 2016 at 7:20

Grey

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Sebastian Simon · Accepted Answer · 2016-12-01 07:54:50Z

0

Ternary operator will work just fine

yourVar = (isNaN(yourVar)) ? 0 : yourVar

So if you want to check if your textbox value is empty or not, you can use:

val = your_textbox_value == '' ? 0 : your_textbox_value

edited Dec 1, 2016 at 7:54

Sebastian Simon

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answered Dec 1, 2016 at 7:28

mrid

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Comments

Paul Roub · Accepted Answer · 2018-10-15 13:47:42Z

0

assign that object to it this will work fine

you_object = you_object == null ? "0" : you_object;

edited Oct 15, 2018 at 13:47

Paul Roub

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answered Oct 15, 2018 at 13:40

Muhammad Bilal

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