python-like generators in javascript

gen.js

function* imap(iterable, func) {
    for (item of iterable) {
        yield func(item);
    }
}

function* ifilter(iterable, predicate) {
    for (item of iterable) {
        if(predicate(item)) {
            yield item;
        }
    }
}

function isome(iterable, predicate) { // [n] => boolean
    for (let item of iterable) {
        if (predicate(item)) {
            return true;
        }
    }

    return false;
}

const nums = range(100);

let f1 = 0;
let f2 = 0;
let f3 = 0;
let f4 = 0;

const something = nums.filter(n => {
    f1++;
    return n > 10;
}).filter(n => {
    f2++;
    return n < 90;
}).some(n => n === 11);

console.log(f1);
console.log(f2);
console.log(something);

const projection = isome(ifilter(ifilter(nums, n => {
    f3++;
    return n > 10;
}), n => {
    f4++;
    return n < 90;
}), n => n === 11);

console.log(f3);
console.log(f4);
console.log(projection);