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);