And so this is a perfect abstraction to make something non- obvious obvious.
The real question is why this shouldn’t be part of the interpreter?
Yes the dependency on isOdd is needless, but is a red herring.
Most commenters here didn’t look deep enough, sadly.
isOdd coerces to a number using Math.abs, so the string checks in isNumber don't apply.
function isOdd(value) {
const n = Math.abs(value);
if (!isNumber(n)) {
throw new TypeError('expected a number');
}
if (!Number.isInteger(n)) {
throw new Error('expected an integer');
}
if (!Number.isSafeInteger(n)) {
throw new Error('value exceeds maximum safe integer');
}
return (n % 2) === 1;
}
function isNumber(num) {
if (typeof num === 'number') {
return num - num === 0;
}
if (typeof num === 'string' && num.trim() !== '') {
return Number.isFinite ? Number.isFinite(+num) : isFinite(+num);
}
return false;
}