AppScript to Hide Rows

I’ve been trying to make the below script work but at the minute it’s hiding all my rows, instead of just the ones that have a value in column U between 30 and 100.

function ReadinghideRows() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var s = ss.getSheetByName('Reading');
  var r = s.getRange('U:U');
  var v = r.getValues();
  for(var i=v.length-1;i>=0;i--)
    if(v[0,i]>'30'<'100')
      s.hideRows(i+1);
};

Are you able to help?

Thank you!

This is the updated version but unfortunately it isn't working (I done something wrong on the code)

function ReadinghideRows() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var s = ss.getSheetByName('Reading');
  var r = s.getRange('U:U');
  var v = r.getValues();
  for(var i=v.length-1;i>=0;i--)
    if 30 < v[0, i] && v[0, i] < 100)
      s.hideRows(i+1);
};

Found the error.... just a missing ( , it should have been like this:

function ReadinghideRows() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var s = ss.getSheetByName('Reading');
  var r = s.getRange('U:U');
  var v = r.getValues();
  for(var i=v.length-1;i>=0;i--)
    if (30 < v[0, i] && v[0, i] < 100)
      s.hideRows(i+1);
};

Thank you all!