Cross-Platform price formatter in 'ru-RU' locale. Covered by unit tests on Jest

getPriceInRU.js

import numberFormat from './numberFormat';

/**
 * Returns price in format '1 000 000 000'
 * @param {Number|String} price
 * @returns {String}
 */
export default function getPriceInRU(price) {
    return numberFormat(price, 0, ',', ' ')
}

getPriceInRu.js

import numberFormat from './numberFormat';

/**
 * Returns price in format '1 000 000 000'
 * @param {Number|String} price
 * @returns {String}
 */
export default function getPriceInRU(price) {
    return numberFormat(price, 0, ',', ' ')
}

getPriceInRU.test.js

import getPriceInRU from './getPriceInRU';

describe('getPriceInRU(Number)', () => {
    it('should return "0"', () => {
        expect(getPriceInRU(0)).toBe("0");
    });
    it('should return "1"', () => {
        expect(getPriceInRU(1)).toBe("1");
    });
    it('should return "10"', () => {
        expect(getPriceInRU(10)).toBe("10");
    });
    it('should return "100"', () => {
        expect(getPriceInRU(100)).toBe("100");
    });
    it('should return "1 000"', () => {
        expect(getPriceInRU(1000)).toBe("1 000");
    });
    it('should return "10 000"', () => {
        expect(getPriceInRU(10000)).toBe("10 000");
    });
    it('should return "100 000"', () => {
        expect(getPriceInRU(100000)).toBe("100 000");
    });
    it('should return "1 000 000"', () => {
        expect(getPriceInRU(1000000)).toBe("1 000 000");
    });
    it('should return "10 000 000"', () => {
        expect(getPriceInRU(10000000)).toBe("10 000 000");
    });
    it('should return "100 000 000"', () => {
        expect(getPriceInRU(100000000)).toBe("100 000 000");
    });
    it('should return "1 000 000 000"', () => {
        expect(getPriceInRU(1000000000)).toBe("1 000 000 000");
    });
    it('should return "10 000 000 000"', () => {
        expect(getPriceInRU(10000000000)).toBe("10 000 000 000");
    });
    it('should return "100 000 000 000"', () => {
        expect(getPriceInRU(100000000000)).toBe("100 000 000 000");
    });
});

describe('getPriceInRU(String)', () => {
    it('should return "0"', () => {
        expect(getPriceInRU("0")).toBe("0");
    });
    it('should return "1"', () => {
        expect(getPriceInRU("1")).toBe("1");
    });
    it('should return "10"', () => {
        expect(getPriceInRU("10")).toBe("10");
    });
    it('should return "100"', () => {
        expect(getPriceInRU("100")).toBe("100");
    });
    it('should return "1 000"', () => {
        expect(getPriceInRU("1000")).toBe("1 000");
    });
    it('should return "10 000"', () => {
        expect(getPriceInRU("10000")).toBe("10 000");
    });
    it('should return "100 000"', () => {
        expect(getPriceInRU("100000")).toBe("100 000");
    });
    it('should return "1 000 000"', () => {
        expect(getPriceInRU("1000000")).toBe("1 000 000");
    });
    it('should return "10 000 000"', () => {
        expect(getPriceInRU("10000000")).toBe("10 000 000");
    });
    it('should return "100 000 000"', () => {
        expect(getPriceInRU("100000000")).toBe("100 000 000");
    });
    it('should return "1 000 000 000"', () => {
        expect(getPriceInRU("1000000000")).toBe("1 000 000 000");
    });
    it('should return "10 000 000 000"', () => {
        expect(getPriceInRU("10000000000")).toBe("10 000 000 000");
    });
    it('should return "100 000 000 000"', () => {
        expect(getPriceInRU("100000000000")).toBe("100 000 000 000");
    });
});

numberFormat.js

/**
 * Format a number with grouped thousands.
 *
 * It is an analog of php's number_format:
 * @see https://www.php.net/manual/en/function.number-format.php
 *
 * @param {Number|String} number The number being formatted
 * @param {Number} decimals Sets the number of decimal points
 * @param {String} decPoint Sets the separator for the decimal point
 * @param {String} thousandsSep Sets the thousands separator
 * @returns {String}  A formatted version of number
 */
export default function numberFormat(number, decimals, decPoint, thousandsSep) {
    var i, j, kw, kd, km;

    if (isNaN(decimals = Math.abs(decimals))) {
        decimals = 2;
    }
    if (decPoint == undefined) {
        decPoint = ",";
    }
    if (thousandsSep == undefined) {
        thousandsSep = ".";
    }

    i = parseInt(number = (+number || 0).toFixed(decimals)) + "";

    if ((j = i.length) > 3) {
        j = j % 3;
    } else {
        j = 0;
    }

    km = (j ? i.substr(0, j) + thousandsSep : "");
    kw = i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thousandsSep);
    kd = (decimals ? decPoint + Math.abs(number - i).toFixed(decimals).replace(/-/, 0).slice(2) : "");

    return km + kw + kd;
}

numberFormat.test.js

import numberFormat from './numberFormat';

describe('numberFormat()', () => {
    it('should work correctly without additional params', () => {
        expect(numberFormat(1000)).toBe('1.000,00');
        expect(numberFormat(1234.56)).toBe('1.234,56');
        expect(numberFormat('1.2000')).toBe('1,20');
    });
    it('should work correctly with additional params', () => {
        expect(numberFormat(1234.56, 2, ',', ' ')).toBe('1 234,56');
        expect(numberFormat(1234.5678, 2, '.', '')).toBe('1234.57');
        expect(numberFormat(67, 2, ',', '.')).toBe('67,00');
        expect(numberFormat(67.311, 2)).toBe('67,31');
        expect(numberFormat(1000.55, 1)).toBe('1.000,5');
        expect(numberFormat(67000, 5, ',', '.')).toBe('67.000,00000');
        expect(numberFormat(0.9, 0)).toBe('1');
        expect(numberFormat('1.20', 2)).toBe('1,20');
        expect(numberFormat('1000.50', 2, '.', ' ')).toBe('1 000.50');
    });
});