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Note at 1:40
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main.js
run
preview
console
function alphabetSubsequence(str) {
if (! /^\w*$/.test(str)) {
console.log('Error: Non-alphabet characters in string.')
return null
}
const testStr = str.toLowerCase()
let currentCharCode = testStr.charCodeAt(0)
for (let i = 1; i < str.length; i++) {
let nextCharCode = testStr.charCodeAt(i)
if (nextCharCode <= currentCharCode) {
return false
}
currentCharCode = nextCharCode
}
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);
});
it('returns null if a non-alphabet character in string', () => {
// arrange
const str = 'abc123!%';

// act
const result = alphabetSubsequence(str);

// log
console.log("result 4: ", result);

// assert
expect(result).toBe(null);
});
});
Console
"result 3: "
,
true
,
"Error: Non-alphabet characters in string."
,
"result 4: "
,
null
,
"result 1: "
,
false
,
"result 2: "
,
false
,
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