var input = document.querySelector("#input");
var output = document.querySelector("#output");
document.querySelector("#button").addEventListener("click",capitalize);

function capitalize(){
    var out="";
    var a = input.value ;
    console.log(a);
    for(var i=0;i<a.length;i++)
        out+= a[i].toUpperCase();
    output.value = out;
}