@naturalcycles/js-lib/dist/array/range.js

Standard library for universal (browser + Node.js) javascript

import { AsyncIterable2 } from '../iter/asyncIterable2.js';
import { Iterable2 } from '../iter/iterable2.js';
export function _range(fromIncl, toExcl, step = 1) {
    if (toExcl === undefined) {
        toExcl = fromIncl;
        fromIncl = 0;
    }
    const a = [];
    for (let i = fromIncl; i < toExcl; i += step) {
        a.push(i);
    }
    return a;
}
/**
 * Returns an array of `length` filled with `fill` primitive value.
 * Performance-optimized implementation.
 * `Array.from({ length }, () => fill)` shows ~25x perf regression in benchmarks
 *
 * Fill is Primitive, because it's safe to shallow-copy.
 * If it was an object - it'll paste the same object reference, which can create bugs.
 */
export function _arrayFilled(length, fill) {
    return Array(length).fill(fill);
}
export function _rangeIterable(fromIncl, toExcl, step = 1) {
    if (toExcl === undefined) {
        toExcl = fromIncl;
        fromIncl = 0;
    }
    return Iterable2.of({
        *[Symbol.iterator]() {
            for (let i = fromIncl; i < toExcl; i += step) {
                yield i;
            }
        },
    });
}
export function _rangeAsyncIterable(fromIncl, toExcl, step = 1) {
    if (toExcl === undefined) {
        toExcl = fromIncl;
        fromIncl = 0;
    }
    return AsyncIterable2.of({
        async *[Symbol.asyncIterator]() {
            for (let i = fromIncl; i < toExcl; i += step) {
                yield i;
            }
        },
    });
}