Ninja Forms phone validation to block specific starting numbers (0, 1, 88) — prevent phone inputs starting with blocked digits on masked Ninja Forms fields

ninja-forms-phone-field-starting-digits-blocker.js

/**
 * Ninja Forms Phone Starting Digits Blocker
 * @author Faisal Ahammad <me@faisalahammad.com)
 */

jQuery(document).ready(function($) {
    
    // Configuration: Add numbers you want to block from starting the phone number
    const BLOCKED_STARTING_NUMBERS = ['0', '1', '88'];
    
    function initPhoneValidation() {
        let phoneInput = $('.phone-container .phone-wrap input.ninja-forms-field');
        
        if (phoneInput.length > 0) {
            phoneInput.each(function() {
                const $input = $(this);
                
                $input.off('.phoneValidation');
                
                $input.on('keypress.phoneValidation keydown.phoneValidation', function(e) {
                    if (BLOCKED_STARTING_NUMBERS.includes(e.key)) {
                        const value = $(this).val();
                        const cursorPos = $(this).prop('selectionStart');
                        const digitsOnly = value.replace(/\D/g, '');
                        
                        if (value.includes('(') && value.includes(')')) {
                            if (cursorPos <= 1) {
                                e.preventDefault();
                                return false;
                            }
                        } else {
                            if (digitsOnly.length === 0) {
                                e.preventDefault();
                                return false;
                            }
                        }
                    }
                    
                    // Handle multi-digit blocked numbers like '88'
                    const value = $(this).val();
                    const digitsOnly = value.replace(/\D/g, '');
                    const potentialStart = digitsOnly + e.key;
                    
                    BLOCKED_STARTING_NUMBERS.forEach(blocked => {
                        if (blocked.length > 1 && potentialStart.startsWith(blocked)) {
                            e.preventDefault();
                            return false;
                        }
                    });
                });
                
                $input.on('input.phoneValidation', function(e) {
                    const value = $(this).val();
                    const digitsOnly = value.replace(/\D/g, '');
                    let shouldClean = false;
                    let cleanedDigits = digitsOnly;
                    
                    // Check if starts with any blocked number
                    BLOCKED_STARTING_NUMBERS.forEach(blocked => {
                        if (digitsOnly.startsWith(blocked)) {
                            cleanedDigits = digitsOnly.substring(blocked.length);
                            shouldClean = true;
                        }
                        
                        // Handle masked input format
                        if (value.startsWith('(' + blocked)) {
                            const newValue = value.replace('(' + blocked, '(');
                            $(this).val(newValue);
                            setTimeout(() => {
                                this.setSelectionRange(1, 1);
                            }, 1);
                            shouldClean = false; // Already handled
                        }
                    });
                    
                    if (shouldClean && cleanedDigits !== digitsOnly) {
                        $(this).focus().val('');
                        
                        setTimeout(() => {
                            $(this).val(cleanedDigits);
                            $(this).trigger('input');
                        }, 10);
                    }
                });
                
                $input.on('focus.phoneValidation', function() {
                    const value = $(this).val();
                    if (value === '(000) 000-0000' || value.includes('000')) {
                        setTimeout(() => {
                            this.setSelectionRange(1, 1);
                        }, 1);
                    }
                });
            });
            
            return true;
        }
        return false;
    }
    
    initPhoneValidation();
    setTimeout(initPhoneValidation, 100);
    setTimeout(initPhoneValidation, 500);
    setTimeout(initPhoneValidation, 1000);
});