Result
let data1 = [11,22,33,44,55]
let data2 = [66,77,88,99]
let data =[];
for(let i=0; i<data1.length; i++){
data[i]=data1[i];
}
for(let i=0; i<data2.length; i++){
data[data1.length+i]=data2[i];
}
console.log(data)