<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Write a JavaScript code snippet to validate a string for a US phone number.
<|im_end|>
<|im_start|>assistant
function validatePhoneNumber(phoneNumber) {
    const regExNumeric = /^[0-9]{10}$/;
    const regExFormatted = /^\d{3}-\d{3}-\d{4}$/;
    
    return (regExNumeric.test(phoneNumber) || regExFormatted.test(phoneNumber));
}<|im_end|>
