how to add data to google sheet with google app script code example

Example 1: read every cell in a column google app script

function appendString() {
    var range = SpreadsheetApp.getActiveSheet().getActiveRange();
    var values = range.getValues();

    values.forEach(function(row, rowId) {
        row.forEach(function(col, colId) {
            values[rowId][colId] += " string";
        });
    });

    range.setValues(values);
}

Example 2: read every cell in a column google app script

function appendString() {
  const range = SpreadsheetApp.getActiveSheet().getActiveRange();
  const values = range.getValues();
  const modified = values.map(row => row.map(currentValue => currentValue + " string"));
  range.setValues(modified);
}