JSFiddle - React, Tailwind, and code Playground

HTML

<!-- Try with One and 3 -->
Choose one,two,three,..,fifty:<br>
<input type='text' id='name'><br>
Choose index:<br>
<input type='number' id='index'><br>
<input type='button' onclick='fun();' value='Go'>

<p>a=
<span id='para2'></span>
</p>
<p>Index=
<span id='para3'></span>
</p>
<p>
a[index] :
<span id='para'></span>
</p>

CSS

p{
  border:1px dotted black;
}

JavaScript

var arrayOne=['mango','banana','pine','orange'];
var arrayTwo=['adobe','microsoft','apple','yahoo'];
var arrayThree=['england','china','nepal','japan','usa','india'];
// suppose i have many more arrayFour,arrayFive,....,arrayFifty

function fun(){
var index=document.getElementById('index').value;
var name=document.getElementById('name').value;
var a='array'+name;
var b=a[index];
document.getElementById('para').innerHTML=b;
document.getElementById('para3').innerHTML=index;
document.getElementById('para2').innerHTML=a;

}