const dfd = require("danfojs-node")
let data = [['K0', 'k0', 'A0', 'B0'], ['k0', 'K1', 'A1', 'B1'],
['K1', 'K0', 'A2', 'B2'], ['K2', 'K2', 'A3', 'B3']]
let data2 = [['K0', 'k0', 'C0', 'D0'], ['K1', 'K0', 'C1', 'D1'],
['K1', 'K0', 'C2', 'D2'], ['K2', 'K0', 'C3', 'D3']]
let colum1 = ['Key1', 'Key2', 'A', 'B']
let colum2 = ['Key1', 'Key2', 'A', 'D']
let df1 = new dfd.DataFrame(data, { columns: colum1 })
let df2 = new dfd.DataFrame(data2, { columns: colum2 })
let com_df = dfd.concat({ dfList: [df1, df2], axis: 1 })