Iterplus

The best of Rust/Haskell/Python iterators in Javascript.

Why Iterplus?

Javascript iterators are weak. Really weak. Like, the only method they have is to get the next value levels of weak. To make matters worse, non-Array containers in Javascript have little to no utility methods, making using them incredibly clunky. By adding powerful functionality to iterators, every single data container gains additional functionality. Also, iterators are lazy, which means they save memory and avoid unnecessary calculations.

Installation

Iterplus is available on npm! Just install it with:

npm install iterplus

You can also find a deno-compatible version on deno.land:

https://deno.land/x/iterplus@v3.0.2/index.ts

It can also be bundled for the web, but you'll have to figure that out for now.

Sample Code

Here are some Leetcode problems solved using iterplus (you can find these in samples/):

// https://leetcode.com/problems/longest-common-prefix/
import {iterplus} from "iterplus";

function longestCommonPrefix(strs: string[]): string {
    return iterplus(strs[0])
        .zip(...strs.slice(1))
        .takeWhile(x => x.every(v => v === x[0]))
        .map(x => x[0])
        .collect()
        .join("");
}

console.log(longestCommonPrefix(["flower","flow","flight"]) || "(nothing)"); // fl
console.log(longestCommonPrefix(["dog","racecar","car"]) || "(nothing)"); // (nothing)

---

// https://leetcode.com/problems/implement-strstr/
import {range} from "iterplus";

function strStr(haystack: string, needle: string): number {
    return range(haystack.length)
        .findIndex(i => haystack.substr(i, needle.length) === needle);
}

console.log(strStr("hello", "ll")); // 2
console.log(strStr("chicken", "c")); // 0
console.log(strStr("chicken", "d")); // -1

---

// https://leetcode.com/problems/search-insert-position/
import {iterplus} from "iterplus";

function searchInsert(nums: number[], target: number): number {
    return iterplus(nums)
        .concat([Infinity])
        .enumerate()
        .skipWhile(([_, v]) => v < target)
        .nextVal()![0];
}

console.log(searchInsert([1, 3, 5, 6], 5)); // 2
console.log(searchInsert([1, 3, 5, 6], 2)); // 1
console.log(searchInsert([1, 3, 5, 6], 7)); // 4
console.log(searchInsert([1, 3, 5, 6], 0)); // 0

Documentation

You can find the generated docs at https://aplet123.github.io/iterplus/.