brn exports only one function that takes a test, a left, and a right
function and return a combined one that will run left if test returns truthy
and right otherwise
const brn = require('brn');
const isOdd = x => x % 2;
const left = x => `${x} is odd`;
const right = x => `${x} is even`;
const fn = brn(isOdd, left, right);
console.log(fn(2)); // returns 2 is even
console.log(fn(1)); // returns 1 is oddimport brn from 'brn'
const isOdd = (x: number) => x % 2;
const fn = brn(
isOdd,
x => `${x} is odd` as const,
x => `${x} is even` as const
);
expect(fn(2, 'two')).toBe('2 is even'); // returns 2 is even
expect(fn(1, 'one')).toBe('1 is odd'); // returns 1 is oddIn this example, parameter x in the "left" and "right" functions is typed as number.
fn also has return type of `${number} is even` | `${number} is odd`
// another example
function always<X extends string>(x: X) {
return () => x;
}
const fn = brn(
(x: number) => x >= 10,
always(`double digit`),
brn(
x => x < 0,
always('negative'),
always('single digit')
)
)In this example, return type of fn is one of "single digit", "double digit" or "negative".