How to compare two column in a spreadsheet -

i have 30 columns , 1000 rows, compare column1 column. if value dont match colour red. below small dataset in spreadsheet:

            b      c      d   e   f    ... 1    name   sname   email  2 3 . n 

because have large dataset , want storing columns in array, first row heading. have done, when testing empty result, can correct me doing wrong?

var index = [];  var sheet = spreadsheetapp.getactivesheet();    function col(){      var data = sheet.getdatarange().getvalues();    (var = 1; <= data.length; i++) {          te = index[i] = data[1];          logger.log(columnindex[i])          if (data[3] != data[7]){              // column_id.setfontcolor('red');  <--- can set background          }      }    }

from code can see scanning whole spreadsheet data[1] heading , in if loop (data[3] != data[7]) compare 2 columns. have work on colour variable can done once data need.

try check tutorial if can problem. tutorial use google appsscript compare 2 columns. if differences found, script should point these out. if no differences found @ all, script should put out text "[id]". customize code own function.

here code used achieve kind of comparison

function stringcomparison(s1, s2) {   // lets test both variables same object type if not throw error   if (object.prototype.tostring.call(s1) !== object.prototype.tostring.call(s2)){     throw("both values need array of cells or individual cells")   }   // if looking @ 2 arrays of cells make sure sizes match , 1 column wide   if( object.prototype.tostring.call(s1) === '[object array]' ) {     if (s1.length != s2.length || s1[0].length > 1 || s2[0].length > 1){       throw("arrays of cells need same size , 1 column wide");     }     // since working array intialise return     var out = [];     (r in s1){ // loop on rows , find differences using diff sub function       out.push([diff(s1[r][0], s2[r][0])]);     }     return out; // return response   } else { // working 2 cells return diff     return diff(s1, s2)   } }  function diff (s1, s2){   var out = "[ ";   var notid = false;   // loop match each character   (var n = 0; n < s1.length; n++){     if (s1.charat(n) == s2.charat(n)){       out += "–";     } else {       out += s2.charat(n);       notid = true;     } out += " ";   }   out += " ]"   return (notid) ? out :  "[ id. ]"; // if notid(entical) return output or [id.] } 

for more information, check tutorial link above , so question on how compare 2 spreadsheets.