Addition operation in angular2 using typescript

Question

I wrote a component like below:

export class AppComponent {
    public num1: number = 2;
    public num2: number = 3;
    public sum: number = 0;
    public add() {
        this.sum = this.num1 + this.num2;
    }
}

For this, I'm getting sum as 23 instead of 5. Give me a proper solution to do addition. I will be glad to know the answer

I don't see any problems here: plnkr.co/edit/ZE9MuIQKQaUUc39ptJ5u?p=preview — eko
– eko, Commented Nov 11, 2016 at 9:55
See Nitzan Tomer's answer for why your TypeScript variables declared as numbers can be treated as strings: stackoverflow.com/questions/39269701/… — Ralph
– Ralph, Commented Oct 4, 2017 at 22:02

danday74 · Accepted Answer · 2016-11-11 09:55:28Z

5

this is because your numbers are being treated as strings.

so its doing "2" + "3" = "23"

to force a number use parseInt function or do ...

this.sum = +this.num1 + +this.num2;

or this should work too ...

this.sum = +this.num1 + this.num2;

edited Nov 11, 2016 at 9:55

answered Nov 11, 2016 at 9:54

danday74

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3 Comments

eko Over a year ago

According to the question, they aren't strings.

Matthias247 Over a year ago

The question has most likely not the full code. I would expect the same reason that's provided in the answer.

danday74 Over a year ago

isNaN("2") === false

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