I have a task to create a countdown iterator that counts from a to b. For example:
console.log([...countdown(10, 1)]); // [10,9,8,7,6,5,4,3,2,1]
const counter = countdown(5,2);
console.log(counter.next()); // {value: 5, done: false};
And i have the next test units:
describe('countdown', () => {
it('should return [10,9,8,7,6,5,4,3,2,1] for given input (10, 1)', () => {
assert.deepStrictEqual([...countdown(10, 1)], [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]);
});
it('should return [5,4,3,2,1,0] for given input (5, 0)', () => {
assert.deepStrictEqual([...countdown(5, 0)], [5, 4, 3, 2, 1, 0]);
});
it('should return [15,14,13,12,11,10] for given input (15, 10)', () => {
assert.deepStrictEqual([...countdown(15, 10)], [15, 14, 13, 12, 11, 10]);
});
it('should return {value: 3, done: false} for given input (3, 0)', () => {
assert.deepStrictEqual(countdown(3, 0).next(), {value: 3, done: false});
});
});
I created the iterator this way :
function countdown(a:number, b:number) {
let arr = [];
while(a>=b){
arr.push(a--)
}
// const next = () =>{
// }
return arr
}
It passes the unit tests,but the problem is,how to create .next() like in the example and show that object with the start value and done ? Thanks in advance! I'm new in TypeScript and i dont know how to do this
You are looking for a generator function:
function* countdown(a:number, b:number) {
while(a>=b){
yield a--;
}
}
console.log([...countdown(10, 1)]);