date-limits/dist/esm/generators/year-generator.js

Check if a date is before a flexible limit.

export function* makeYearGenerator(config = undefined, startFrom, lowerLimit = 1970) {
    if (config === undefined) {
        let currentNum = startFrom;
        while (currentNum >= lowerLimit) {
            yield currentNum--;
        }
        return null;
    }
    if (typeof config === 'number') {
        if (config <= startFrom) {
            yield config;
        }
        return null;
    }
    if (Array.isArray(config)) {
        for (let i = config.length; i >= 0; i--) {
            if (config[i] > startFrom)
                continue;
            yield config[i];
        }
        return null;
    }
    if ('slope' in config) {
        const { slope: a, offset: b = 0 } = config;
        const x = Math.floor((startFrom - b) / a);
        let currentNum = a * x + b;
        while (currentNum >= lowerLimit) {
            yield currentNum;
            currentNum -= a;
        }
        return null;
    }
    config.from ?? (config.from = lowerLimit);
    config.to ?? (config.to = startFrom);
    if (config.from > startFrom) {
        return null;
    }
    if (config.from > config.to) {
        throw new Error(`Config range cannot contain "from" value higher than "to" value, got ${config.from} and ${config.to} respectively.`);
    }
    let currentNum = startFrom > config.to ? config.to : startFrom;
    // if config.from > startFrom then the loop will never run
    while (currentNum >= config.from) {
        yield currentNum--;
    }
    return null;
}