Normal and Functional Approach of Add/Replace Data Patten at JavaScript

index.js

var oldDB = [
  {
    index: 1,
    name: "Java"
  },
  {
    index: 2,
    name: "C"
  },
  {
    index: 5,
    name: "Rust"
  }
];

var newDB = [
  {
    index: 1,
    name: "JavaScript"
  },
  {
    index: 3,
    name: "Ruby"
  }
];

function addOrReplaceWithIndex_NormalApproach(oldData, newData){
  
  var filteredOldData = [];
  
  for (var i = 0; i < oldData.length; i++) {
    var odata = oldData[i];
    var _index = odata.index;
    
    // Filtering not match with new data
    var match = false;
    
    for (var j = 0; j < newData.length; j++) {
      var ndata = newData[j];
      
      if(ndata.index === _index){
        match = true;
        break;
      }
    }
    
    if( !match )
      filteredOldData.push( odata );
  }
  
  return filteredOldData.concat( newData );
}

function addOrReplaceWithIndex_FunctionalApproach(oldData, newData){
  
  // Filtering not match with new data
  var _filter = oldData.filter(function( odata ){
    
    /*
     * NOTE: We can't do "Some of newData is not match with odata"
     */
    var indexIsIncludeInNewData = newData.some(function( ndata ){
      return ndata.index === odata.index;
    });
    
    return !indexIsIncludeInNewData;
  });
  
  return _filter.concat( newData );
  
}

console.dir( addOrReplaceWithIndex_NormalApproach(oldDB, newDB) );
console.dir( addOrReplaceWithIndex_FunctionalApproach(oldDB, newDB) );