function alphabetSubsequence(str) {
    let isAlphaSeq = false;
    const STR = str.toUpperCase();
    for (i = 0; i < STR.length; i++) {
        const charCode = STR.charCodeAt(i);
        if (charCode >= 65 && charCode <= 90) {
            if (i > 0) {
                if (charCode > STR.charCodeAt(i - 1)) {
                    if (i === (STR.length - 1)) {
                        isAlphaSeq = true;
                    } else {
                        continue;
                    }
                } else {
                    break;
                }
            }
        } else {
            break;
        }
    }
    return isAlphaSeq;
}



/**
* 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';
        
        // act
        const result = alphabetSubsequence(str);

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