Algorithms and Data Structures implemented in JavaScript for beginners, following best practices.
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// function that takes 10 digits and returns a string of the formatted phone number
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// e.g.: 1234567890 -> (123) 456-7890
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const formatPhoneNumber = (numbers) => {
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const numbersString = numbers.toString()
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if ((numbersString.length !== 10) || isNaN(numbersString)) {
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// return "Invalid phone number."
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throw new TypeError('Invalid phone number.')
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}
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const arr = '(XXX) XXX-XXXX'.split('')
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Array.from(numbersString).forEach(n => {
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arr[arr.indexOf('X')] = n
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})
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return arr.join('')
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}
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export { formatPhoneNumber }
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