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algorithm: count letters #1164

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Merged
raklaptudirm merged 9 commits into from
Oct 19, 2022
Merged

algorithm: count letters #1164

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dcf7a11
feat: Add countCharacters algorithm
sandra-laguna Oct 10, 2022
92e20be
tests: Add countCharacters tests
sandra-laguna Oct 10, 2022
0ecc0d7
change var to let
sandra-laguna Oct 10, 2022
48961e5
change let to const
sandra-laguna Oct 10, 2022
664b0da
fix: regEx
sandra-laguna Oct 10, 2022
cf56c3c
fix: change line
sandra-laguna Oct 11, 2022
25891c6
replace if-else condition
sandra-laguna Oct 11, 2022
de70332
refactor: Change name to CountLetters
sandra-laguna Oct 17, 2022
fe3017b
fix: change "characters" for "letters"
sandra-laguna Oct 17, 2022
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33 changes: 33 additions & 0 deletions String/CountLetters.js
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Original file line number Diff line number Diff line change
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/**
* @function countLetters
* @description Given a string, count the number of each letter.
* @param {String} str - The input string
* @return {Object} - Object with letters and number of times
* @example countLetters("hello") => {h: 1, e: 1, l: 2, o: 1}
*/

const countLetters = (str) => {
const specialChars = /\W/g

if (typeof str !== 'string') {
throw new TypeError('Input should be a string')
}

if (specialChars.test(str)) {
throw new TypeError('Input must not contain special characters')
}

if (/\d/.test(str)) {
throw new TypeError('Input must not contain numbers')
}

const obj = {}
for (let i = 0; i < str.toLowerCase().length; i++) {
const char = str.toLowerCase().charAt(i)
obj[char] = (obj[char] || 0) + 1
}

return obj
}

export { countLetters }
33 changes: 33 additions & 0 deletions String/test/CountLetters.test.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
import { countLetters } from '../CountLetters'

describe('CountLetters', () => {
it('expect throws on use wrong param', () => {
expect(() => countLetters(0)).toThrow()
})

it('expect throws when using a number in the string', () => {
expect(() => countLetters('h3llo')).toThrow()
})

it('expect throws when using a special characters in the string', () => {
expect(() => countLetters('hello!')).toThrow()
})

it('count the letters in a string. Allows lower case', () => {
const value = 'hello'
const count = countLetters(value)
expect(count).toEqual({ h: 1, e: 1, l: 2, o: 1 })
})

it('count the letters in a string. Allows upper case', () => {
const value = 'HELLO'
const count = countLetters(value)
expect(count).toEqual({ h: 1, e: 1, l: 2, o: 1 })
})

it('count the letters in a string. Allows upper and lower case', () => {
const value = 'HelLo'
const count = countLetters(value)
expect(count).toEqual({ h: 1, e: 1, l: 2, o: 1 })
})
})