Large number format filter for Angular written in ES6 that rounds to the specified decimal place (defaults to 1). 1 billion => 1B, 1,490,000 => 1.5M, 999,999 => 1M

megaNumber.js

angular.module('utilsModule').filter("megaNumber", () => {
    return (number, fractionSize) => {

        if(number === null) return null;
        if(number === 0) return "0";

        if(!fractionSize || fractionSize < 0)
            fractionSize = 1;

        var abs = Math.abs(number);
        var rounder = Math.pow(10,fractionSize);
        var isNegative = number < 0;
        var key = '';
        var powers = [
            {key: "Q", value: Math.pow(10,15)},
            {key: "T", value: Math.pow(10,12)},
            {key: "B", value: Math.pow(10,9)},
            {key: "M", value: Math.pow(10,6)},
            {key: "K", value: 1000}
        ];

        for(var i = 0; i < powers.length; i++) {

            var reduced = abs / powers[i].value;

            reduced = Math.round(reduced * rounder) / rounder;

            if(reduced >= 1){
                abs = reduced;
                key = powers[i].key;
                break;
            }
        }

        return (isNegative ? '-' : '') + abs + key;
    };
});

megaNumber.spec.js

describe('megaNumber tests', function(){

    var $filter, megaNumberFilter;

    beforeEach(module('utilsModule'));

    beforeEach(inject(function(_$filter_){
        $filter = _$filter_;

        megaNumberFilter = $filter('megaNumber');
    }));

    it('1,500,000,000 is converted to 1.5B', function(){
        const value = 1.5 * Math.pow(10,9);
        var result = megaNumberFilter(value);

        expect(result).toBe("1.5B");
    });

    it('1,490,000,000 is rounded to 1.5B', function(){
        const value = 1.49 * Math.pow(10,9);
        var result = megaNumberFilter(value);

        expect(result).toBe("1.5B");
    });

    it('1,550,000,000 is rounded to 1.6B', function(){
        const value = 1.55 * Math.pow(10,9);
        var result = megaNumberFilter(value);

        expect(result).toBe("1.6B");
    });

    it('1,500,000 is converted to 1.5M', function(){
        const value = 1.5 * Math.pow(10,6);
        var result = megaNumberFilter(value);

        expect(result).toBe("1.5M");
    });

    it('1,500 is converted to 1.5K', function(){
        const value = 1.5 * Math.pow(10,3);
        var result = megaNumberFilter(value);

        expect(result).toBe("1.5K");
    });

    it('1,550 is rounded to 1.6K', function(){
        const value = 1.55 * Math.pow(10,3);
        var result = megaNumberFilter(value);

        expect(result).toBe("1.6K");
    });

    it('1,555 is rounded to 1.56K with 2 decimal places', function(){
        const value = 1555;
        var result = megaNumberFilter(value, 2);

        expect(result).toBe("1.56K");
    });

    it('999 is rounded to 1K', function(){
        const value = 999;
        var result = megaNumberFilter(value);

        expect(result).toBe("1K");
    });

    it('990,000 is rounded to 1M', function(){
        const value = 990000;
        var result = megaNumberFilter(value);

        expect(result).toBe("1M");
    });

    it('990,000 is not rounded to 1M if 2 decimal places', function(){
        const value = 990000;
        var result = megaNumberFilter(value, 2);

        expect(result).toBe("990K");
    });

    it('-999 is rounded to -1K', function(){
        const value = -999;
        var result = megaNumberFilter(value);

        expect(result).toBe("-1K");
    });

    it('0 is still 0', function(){
        const value = 0;
        var result = megaNumberFilter(value);

        expect(result).toBe("0");
    });

    it('null is still null', function(){
        var result = megaNumberFilter(null);
        expect(result).toBe(null);
    });

});