US Phone Number Validator

This code provides a simple function to validate whether a given string represents a valid US phone number. It supports multiple formats commonly used in the United States.

Function Signature

function telephoneCheck(str)

Usage

To use the telephoneCheck function, pass a string as an argument representing the phone number you want to validate. The function will return true if the string represents a valid US phone number and false otherwise.

Example

console.log(telephoneCheck("555-555-5555")); // Output: true
console.log(telephoneCheck("(555)555-5555")); // Output: true
console.log(telephoneCheck("1 555 555 5555")); // Output: true
console.log(telephoneCheck("123-456-7890")); // Output: false

Valid US Phone Number Formats

The function `telephoneCheck` validates phone numbers based on the following formats:

• '555-555-5555',
• '(555)555-5555',
• '(555) 555-5555',
• '555 555 5555',
• '5555555555',
• '1 555 555 5555',

The area code is required for all formats. If the country code is provided, it must be "1". The function will return `true` if the string matches any of the valid formats and `false` otherwise.

Implementation Details

The function `telephoneCheck` uses a regular expression to match the given string against the valid US phone number formats. The regular expression pattern `^(1\s?)?(\(\d{3}\)|\d{3})[-\s]?(\d{3})[-\s]?(\d{4})$` is employed for this purpose.

• `^` asserts the start of the string.
• `(1\s?)?` optionally matches the country code "1" followed by an optional space.
• `(\(\d{3}\)|\d{3})` matches either three digits enclosed in parentheses or three consecutive digits.
• `[-\s]?` matches an optional hyphen or space.
• `\d{3}` matches three consecutive digits.
• `[-\s]?` matches an optional hyphen or space.
• `\d{4}` matches four consecutive digits.
• `$` asserts the end of the string.

If the string matches the regular expression pattern, the function returns `true`, indicating a valid US phone number. Otherwise, it returns `false`. `;

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License

This code is provided under the MIT License. Feel free to use and modify it according to your needs.