function deleteEmptyColumns() {

  const sheet = SpreadsheetApp.getActiveSheet();

  // Gets active selection and dimensions.
  let activeRange = sheet.getActiveRange();
  const rowCountMax = sheet.getMaxRows();
  const columnWidth = activeRange.getWidth();
  const firstActiveColumn = activeRange.getColumn();

  // Tests that the selection is a valid range.
  if (columnWidth < 1) {
    showMessage('Select a valid range.');
    return;
  }
  // Tests active range is not too large to process. Enforces limit set to 1k.
  if (columnWidth > 1000) {
    showMessage("Selected range too large. Select up to 10,000 rows at one time.");
    return;
  }

  // Utilizes an array of values for efficient processing to determine blank columns.
  const activeRangeValues = sheet.getRange(1, firstActiveColumn, rowCountMax, columnWidth).getValues();

  // Transposes the array of range values so it can be processed in order of columns.
  const activeRangeValuesTransposed = activeRangeValues[0].map((_, colIndex) => activeRangeValues.map(row => row[colIndex]));

  // Checks if array is all empty values.
  const valueFilter = value => value !== '';
  const isColumnEmpty = (column) => {
    return column.filter(valueFilter).length === 0;
  }

  // Maps the range values as an object with value (to test) and corresponding column index (with offset from selection).
  const columnsToDelete = activeRangeValuesTransposed.map((column, index) => ({ column, offset: index + firstActiveColumn}))
    .filter(item => isColumnEmpty(item.column)) // Test to filter out non-empty rows.
    .map(item => item.offset); //Remap to include just the column indexes that will be removed.

  // Combines a sorted, ascending list of indexes into a set of ranges capturing consecutive values as start/end ranges.
  // Combines sequential empty columns for faster processing.
  const rangesToDelete = columnsToDelete.reduce((ranges, index) => {
    const currentRange = ranges[ranges.length - 1];
    if (currentRange && index === currentRange[1] + 1) {
      currentRange[1] = index;
      return ranges;
    }
    ranges.push([index, index]);
    return ranges;
  }, []);

  // Sends a list of column indexes to be deleted to the console.
  console.log(rangesToDelete);

  // Deletes the columns using REVERSE order to ensure proper indexing is used.
  rangesToDelete.reverse().forEach(([start, end]) => sheet.deleteColumns(start, end - start + 1));
  SpreadsheetApp.flush();
}
Removes blank columns in a selected range.

Cells containing Space characters are treated as non-empty.
The entire column, including cells outside of the selected range,
must be empty to be deleted.
  
Called from menu option.