meows/build/arrays.js

A kittybin of tools.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const types_1 = require("./types");
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// Arrays
/**
 * Shallow filters out redundant members.
 * @example
 * uniques([0, 1, 2, 2, 3, 3])  // => [0, 1, 2, 3]
 */
function uniques(arr) {
    if (!Array.isArray(arr))
        throw new TypeError(`uniques() requires an array, but got: ${arr}.`);
    return [...new Set(arr)];
}
exports.uniques = uniques;
/**
 * Shallow checks for repeat members.
 * @example
 * has_repeat([1, 2, 3])  // => false
 * has_repeat([1, 2, 1])  // => true
 */
function hasRepeat(arr) {
    if (!Array.isArray(arr))
        throw new TypeError(`hasRepeat() requires an array, but got: ${arr}.`);
    return arr.length !== new Set(arr).size;
}
exports.hasRepeat = hasRepeat;
/**
 * Choose random member in array.
 * @example
 * randChoose([1, 'a', null])  // => 1
 * randChoose([1, 'a', null])  // => null
 */
function randChoose(arr) {
    if (types_1.notEmpty.arr(arr))
        throw new TypeError(`randChoose() requires a non-empty array, but got: ${arr}.`);
    return arr[Math.trunc(Math.random() * arr.length)];
}
exports.randChoose = randChoose;
/**
 * A function for quickly generating arrays populated by a range of integers,
 * with an optional skip interval.
 *
 * @example
 * range(3)          // => [0, 1, 2, 3]
 * range(-3)         // => [0, -1, -2, -3]
 * range(-2, 2)      // => [-2, -1, 0, 1, 2]
 * range(2, -2)      // => [2, 1, 0, -1, -2]
 * range(-10, 10, 5) // => [-10, -5, 0, 5, 10]
 * range(10, -10, 5) // => [10, 5, 0, -5, -10]
 */
function range(p0, pf, skip) {
    const direction = pf > p0 ? 1 : -1;
    const beautify = x => x === 0 ? 0 : x;
    switch (arguments.length) {
        case 1: return Array.from({ length: Math.abs(p0) + 1 }, (_, i) => i * Math.sign(p0)).map(beautify);
        case 2: return Array.from({ length: Math.abs(pf - p0) + 1 }, (_, i) => i * direction + p0).map(beautify);
        case 3: return Array.from({ length: Math.abs(Math.abs(pf - p0) / Math.abs(skip) + 1) }, (_, i) => i * skip * direction + p0).map(beautify);
        default: return [];
    }
}
exports.range = range;
/**
 * Uses `λ` to populate an array of `items` length.
 *
 * @example
 * series(x => 0.5*x**2 + 0.5*x, 5)  // => [0, 1, 3, 6, 10]
 */
function series(λ, items = 1) {
    return Array.from({ length: items }, (_, v) => λ(v));
}
exports.series = series;
/**
 * Returns a shallow copy of the last value of your array. The default behavior
 * is to return `undefined` on an empty array while `throwOnEmpty` is set to
 * `false`.
 *
 * @example
 * last([3, 2, 1])       // => 1
 * last([3, 2, [1, 0]])  // => [1, 0]
 * last([null])          // => null
 * last([])              // => undefined if throwOnEmpty is false (!)
 */
function last(arr, throwOnEmpty = false) {
    if (!Array.isArray(arr))
        throw new TypeError(`arr() requires an array, but got: ${arr}.`);
    if (throwOnEmpty && arr.length === 0)
        throw new RangeError(`arr() requires a non-empty array.`);
    return arr.slice(-1)[0];
}
exports.last = last;