How to put restriction in a class constructor?

Question

The constructor function of the Interpolation class takes in two arrays. How can I set a restriction so that during object creation the length of these two arrays must be equal.

class Interpolation {
    constructor (x, fx) {
        if ( x instanceof Array && fx instanceof Array ) {
            if ( x.length === fx.length ) {
                this.input = x;
                this.output = fx;
            } else { throw 'Unmatching array' }
        } else throw 'Please pass in array';
    }
}

I tried this and during object creating the source code was also printed on the console like this

C:\NeuralNetwork\interpolation.js:7
                        } else { throw('Invalid Array') }
                                 ^
Invalid Array

You are already doing that. What is it that you need help with? — gurvinder372, Jan 24 '18 at 09:15
Apart from that [you should not throw strings](https://stackoverflow.com/q/11502052/1048572), your code seems fine? — Bergi, Jan 24 '18 at 09:35
@gurvinder372 My problem is the error is showing the source code which doesn't seem tidy — Aditya, Jan 24 '18 at 15:30
@Aditya That's just the debugger trying to help you, showing where the error originated from and a stack trace. That's what exceptions do. Catch the error and it won't print anything. — Bergi, Jan 25 '18 at 00:48

score 1 · Answer 1 · answered Jan 24 '18 at 09:18

like this:

class Interpolation {
    constructor (x, fx) {
        if(!(x instanceof Array)) {
            throw('parameter `x` must be an Array.');
        }

        if(!(fx instanceof Array)) {
            throw('parameter `fx` must be an Array,');
        }

        if(x.length !== fx.length) {
            throw('the length of these two arrays(x, fx) must be equal');
        }

        this.input = x;
        this.output = fx;
    }
}

How to put restriction in a class constructor?

1 Answers1