textconvert/dist/text/validation/email.js

Public library to convert text into many conventions and formats.

/**
 * Validates if a string is a valid email address according to RFC 5322 standards.
 *
 * This function performs comprehensive validation including:
 * - Basic email structure (local part + @ + domain)
 * - Valid characters in local part and domain
 * - Domain must contain at least one dot
 * - No consecutive dots
 * - No trailing dots or hyphens
 * - Length limits (local part ≤ 64 chars, domain ≤ 255 chars)
 * - Non-ASCII character rejection
 *
 * @param text - The string to validate as an email address
 * @returns boolean indicating if the string is a valid email address
 *
 * @example
 * ```typescript
 * isEmail('user@example.com')     // true
 * isEmail('user.name@example.com') // true
 * isEmail('user+tag@example.com') // true
 * isEmail('plainaddress')         // false
 * isEmail('@example.com')         // false
 * isEmail('user@')               // false
 * ```
 */
export function isEmail(text) {
    if (!text || typeof text !== 'string') {
        return false;
    }
    const email = text.trim();
    // Reject non-ASCII characters
    if (/[^\x20-\x7E]/.test(email)) {
        return false;
    }
    const emailRegex = /^(?!.*\.{2})[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.[a-zA-Z]{2,}$/;
    if (!emailRegex.test(email)) {
        return false;
    }
    const [localPart, domain] = email.split('@');
    if (!localPart || !domain)
        return false;
    if (localPart.length > 64 || domain.length > 255)
        return false;
    if (domain.startsWith('-') || domain.endsWith('-'))
        return false;
    if (domain.startsWith('.') || domain.endsWith('.'))
        return false;
    return true;
}