SOURCE

function writeDocument(variable){
    document.write(variable + "<br/>");
}

var arr = ["HTML","CSS","JavaScript","jQuery","Vue.js"];

writeDocument(arr[2]);

writeDocument(arr);

arr[4] = "React.js";

writeDocument(arr);

arr[5] = "Vue.js";

writeDocument(arr);

arr[8] = "Angular.js";

writeDocument(arr);