locutus/python/math/prod.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.prod = prod;
function prod(values, start = 1) {
    //      discuss at: https://locutus.io/python/prod/
    // parity verified: Python 3.12
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Multiplies all iterable values together and applies the optional start value first.
    //       example 1: prod([2, 3, 4])
    //       returns 1: 24
    //       example 2: prod([], 5)
    //       returns 2: 5
    //       example 3: prod([1.5, 2, 3], 2)
    //       returns 3: 18
    if (!Array.isArray(values)) {
        throw new TypeError('prod(): iterable must be an array');
    }
    let result = start;
    for (const value of values) {
        result = multiplyProdValues(result, value);
    }
    return result;
}
function multiplyProdValues(left, right) {
    if (typeof left === 'string' && typeof right !== 'string') {
        return repeatString(left, right);
    }
    if (typeof right === 'string' && typeof left !== 'string') {
        return repeatString(right, left);
    }
    if (typeof left !== 'number' || typeof right !== 'number') {
        throw new TypeError('prod(): values must be numbers or repeatable strings');
    }
    const leftNumber = left;
    const rightNumber = right;
    if (Number.isInteger(leftNumber) && Number.isInteger(rightNumber)) {
        if (leftNumber === 0 || rightNumber === 0) {
            return 0;
        }
        if (leftNumber === 1) {
            return rightNumber;
        }
        if (rightNumber === 1) {
            return leftNumber;
        }
        if (leftNumber === -1) {
            return -rightNumber;
        }
        if (rightNumber === -1) {
            return -leftNumber;
        }
        if (!Number.isSafeInteger(leftNumber) || !Number.isSafeInteger(rightNumber)) {
            throw new RangeError('prod(): integer multiplication only supports JS safe integers');
        }
        const result = leftNumber * rightNumber;
        if (!Number.isSafeInteger(result)) {
            throw new RangeError('prod(): integer multiplication only supports JS safe integers');
        }
        return result;
    }
    return leftNumber * rightNumber;
}
function repeatString(value, multiplier) {
    if (typeof multiplier !== 'number') {
        throw new TypeError('prod(): string repetition requires a safe integer multiplier');
    }
    const count = multiplier;
    if (!Number.isInteger(count) || !Number.isSafeInteger(count)) {
        throw new TypeError('prod(): string repetition requires a safe integer multiplier');
    }
    return count > 0 ? value.repeat(count) : '';
}