This is fine and works:
const power = (x,n) => {
if (n === 0) return 1;
return x * power(x, n - 1);
}
power(4,3) 64
But trying to do this as experiment - does not work gives NaN Do not understand why:
node .editor // Entering editor mode (Ctrl+D to finish, Ctrl+C to cancel)
const power = x => {
return n => {
if (n === 0) return 1;
return x * power(x, n - 1);
}
}
let t = power(4) t(3) NaN
You haven't converted the recursive call in the curried version to curried form. power(x, n - 1) is essentially the same as power(x) because power only accepts one argument, and this is a function, so not unreasonably becomes NaN when you try to multiply it by a number.
Rewrite it like this instead:
const power = x => {
return n => {
if (n === 0) return 1;
return x * power(x)(n - 1);
}
};
console.log('4^3 = ', power(4)(3)); // 64
console.log('2^10 = ', power(2)(10)); // 1024
console.log('5^4 = ', power(5)(4)); // 625
console.log('3^4 = ', power(3)(4)); // 81You could store the nested function and return the function and use this function for another call with only the changed n.
const
power = x => {
const
fn = n => n === 0
? 1
: x * fn(n - 1);
return fn;
};
console.log(power(4)(3));As we are discussing "weird" function forms I might as well contribute my two cents worth:
You can also do the curried function as a one-liner like this:
const power = (x,pow) => pow = n => --n ? x*pow(n) : x;
console.log(power(3)(4)); // 81This is, of course, something that nobody in their right mind would ever do. Still - it works!