function alphabetSubsequence(str) {
// write code here.
const mySet = new Set();
for (let i=0; i < str.length; i++){
const thisChar = str[i];
if(mySet.has(thisChar)) return false;
mySet.add(thisChar)
}
return true;
}
/**
* 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);
});
});