function regexPhoneNumber(str) {
    const regexPhoneNumber = /^((\+)33|0)[1-9](\d{2}){4}$/; 
  
    if (str.match(regexPhoneNumber)) {
        return true;
    } else {
        return false;
    }
}

let phoneNumber = "+33777777777";
console.log(regexPhoneNumber(phoneNumber));