validate phone number length using jquery not working

function validatePhone(phone) {
  if (phone.value.length <= 10 && phone.value.length >= 5) {
    let
    var = 'Yes';
    return var;
  } else {
    let
    var = 'No';
    return var;
  }
}

function validate() {
  let result1 = $("#result1");
  let phone = $("#phone").val();
  result1.text("");


  if (validatePhone(phone)) {
    result1.text(var);
    result1.css("color", "green");
  }
  return false;
}
jQuery(function($) {
  $("#phone").on("input", validate);
});

<input type="number" class="form-control"  id="phone" name="phone">
<span class="label">Phone Number<span style="color:red">*</span> <span id="result1"></span></span>