function alphabetSubsequence(str) {
    let isNext = false;
    if (str.length > new Set(str).size) {
        return false;
    } else {
        for (let i = 0; i < str.length -1; i++) {
            (str.charCodeAt(i) < str.charCodeAt(i + 1)) ? isNext = true : isNext = false;
            if (!isNext) return isNext;
        }
    }
    return isNext;
}

/**
* Test Suite 
*/
describe('alphabetSubsequence()', () => {
    it('returns false when it has duplicate letters', () => {
        // arrange
        const str = 'effg';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 1: ", result);
        
        // assert
        expect(result).toBe(false);
    });

    it('returns false when NOT in ascending a - z order', () => {
        // arrange
        const str = 'cdce';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 2: ", result);
        
        // assert
        expect(result).toBe(false);
    });
    
    it('returns true whenno duplicates and is ascending a - z order ', () => {
        // arrange
        const str = 'ace';
        //const str = 'acbe';
        // const str = 'acb';
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 3: ", result);
        
        // assert
        expect(result).toBe(true);
        // expect(result).toBe(false);
    });
});