@roninjjj/randomize/dist/index.js

Easily include random number generation in your projects. Whether if it's a 2 item 50/50, or a 20 item lootbox, all you need is a simple object!

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
function randomChance(chances) {
    const chance_sum = Object.values(chances)
        .reduce((acc, curr) => acc + curr);
    if (chance_sum !== 100)
        throw new Error(`Incorrect percentages. Received ${chance_sum} while expecting 100.`);
    const rand = Math.random() * 100; // a number between 0 and 99.9
    let _ = 0;
    const pairs = Object.entries(chances).sort((a, b) => b[1] - a[1]) // { gold: 10, silver: 90 } -> [ ['silver', 90], ['gold', 10] ]
        .reduce((acc, curr) => {
        _ += curr[1];
        acc.push([curr[0], _]);
        return acc;
    }, []); // [ ['silver', 90], ['gold', 10] ] -> [ ['silver', 90], ['gold', 100] ]
    for (const [value, chance] of pairs) {
        if (chance > rand) {
            return value;
        }
    }
    // in case of any unexpected outputs, return the most common item.
    return pairs[0][0];
}
exports.default = randomChance;