run loop through excel and check value equals gscript code example

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

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

  var modified = values.map(function (row) {
    return row.map(function (col) { 
      return col + " string"; 
    }); 
  })

  range.setValues(modified);
}

Example 2: 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);
}