Javascript Object Merger with ES6

object-merger.js

      mergeObject: (obj1 = {}, obj2 = {}) => {
        
       let ObjArray =  [obj1,obj2];
       let key1 =  Object.keys(obj1);
       let key2 =  Object.keys(obj2);
       let unionKeys =  [...new Set([...key1 ,...key2])];
       let ignore    = new Set(['createdAt','updatedAt','updated_at','_id']); 
       let result = {}; 
       let keysMap = new Map();
       unionKeys =  new Set([...unionKeys].filter(x => !ignore.has(x)));
        for (var key of unionKeys) {            
            if (Object.prototype.hasOwnProperty.call(obj2, key)) {
                keysMap.set(`${key}-${utiliy.typechecker(obj2[key])}`,0); 
            } else {
                keysMap.set(`${key}-${utiliy.typechecker(obj1[key])}`,1); 
            }
        }
        // console.log('start')
        for (var [key, from] of keysMap.entries()) {
            
            let [index,type] = key.split('-'); 
            if (type == 'string' || type == 'number' ) {
                result[index] =  ObjArray[1][index];
                if (!result[index]) {
                    result[index] =  ObjArray[0][index];
                }
            } else if (type == 'array') {
                let array1 =   ObjArray[0][index] || [];
                let array2 =   ObjArray[1][index] || [];
                result[index] = [...new Set([...array1 ,...array2])];
                continue; 
            } else if (type == 'object') {
                let subObj1 =  ObjArray[0][index] || {};
                let subObj2 =  ObjArray[1][index] || {}; 
                result[index] =  utiliy.mergeObject(subObj1,subObj2);
            }
        }
        return result; 
          
    },
      
    isEmptyObject : (obj) => {
        return !Object.keys(obj).length;
    },

    
    typechecker: (obj) => {
        return (typeof(obj) === 'object')  ? (Array.isArray(obj)) ? 'array' : 'object' : typeof(obj);
    },