cmp.set('v.customObjectTableColumns', [
                                          {label: 'Name', fieldName: 'Name', type: 'text'},
                                          {label: 'Quantity', fieldName: 'Quantity__c', type: 'number'},
                                          {label: 'Date', fieldName: 'Date__c', type: 'date'}]);

fr.onload = $A.getCallback(function() {
            let fileContents = fr.result;
            let workbook = XLSX.read(fileContents, {
                type: 'binary'
            });
            let rows = XLSX.utils.sheet_to_json(workbook.Sheets[workbook.SheetNames[0]]);
            let customObjects = [];

            for (let i = 0, len = rows.length; i < len; i++) {

                for (let j = 1; j <= 5; j++) {
                    let customObject = {
                        sobjectType: 'customObject__c',
                        Name: rows[i]['Name'],
                        Quantity__c: rows[i]['Quantity']
                        Date__c: rows[i]['Date']
                    };
                    customObjects.push(customObject);
                }
            }
            cmp.set("v.customObjects", customObjects);
        });