User register checking function

function validateInput()
  {
  if(password.value.length < 8){
    messages.push('Please enter a longer password')
  }
  if(email.value.includes('@')==false){
    messages.push('Please enter a correct email')
  }
  if(phone.value.length < 10){
    messages.push('Please enter a valid phone number')
  }
  if(password2.value != password.value){
    messages.push('The passwords dont match')
  }
  if(Fname.value.length < 2 || Lname.value.length < 2){
    messages.push('Please enter a valid name')
  }
  if(code.value==''){
    messages.push('Please select a phone code')
  }
  if(city.value==''){
    messages.push('Please select a city')
  }
  if(gender.value == ''){
    messages.push('Please select a gender')
  }
  if (!(document.getElementById("op1").checked ||                   
        document.getElementById("op2").checked || 
        document.getElementById("op3").checked || 
        document.getElementById("op4").checked || 
        document.getElementById("op5").checked || 
        document.getElementById("op6").checked)){messages.push('Please select relevent prior academic certification')}