zip.js

function zipMin(...iterators) {
    let done = iterators.length === 0;
    iterators = iterators.map(iterator => iterator[Symbol.iterator]());
    return {
        [Symbol.iterator]() {
            return this;
        },
        next(...args) {
            let value = [];
            for (let i = 0, length = iterators.length; i < length; i++) {
                let output = iterators[i].next(...args);
                value[i] = output.value;
                done = done || output.done;
            }
            return { value, done };
        },
        throw(...args) {
            let value = [];
            for (let i = 0, length = iterators.length; i < length; i++) {
                let output = iterators[i].throw(...args);
                value[i] = output.value;
                done = done || output.done;
            }
            return { value, done };
        },
    };
}

function zipMax(...iterators) {
    let done = iterators.length === 0;
    iterators = iterators.map(iterator => iterator[Symbol.iterator]());
    return {
        [Symbol.iterator]() {
            return this;
        },
        next(...args) {
            let value = [];
            let allDone = !done;
            for (let i = 0, length = iterators.length; i < length; i++) {
                let output = iterators[i].next(...args);
                value[i] = output.value;
                allDone = allDone && output.done;
            }
            done = done || allDone;
            return { value, done };
        },
        throw(...args) {
            let value = [];
            let allDone = !done;
            for (let i = 0, length = iterators.length; i < length; i++) {
                let output = iterators[i].next(...args);
                value[i] = output.value;
                allDone = allDone && output.done;
            }
            done = done || allDone;
            return { value, done };
        },
    };
}