How can I use innerhtml in JavaScript?

Question

My problem is that I don\'t know how to show the innerhtml of my form.

The form is like a survey form and once you clicked the submit button, all the contents I had

Answer 1

var maincontent = document.getElementById("content").innerHTML;
maincontent = "
" + first;

On the second line you're overwriting the variable, not setting the .innerHTML. This is what you want:

var maincontent = document.getElementById("content");
maincontent.innerHTML = "
" + first;

Also, you must make sure the elements with ids of "first" "middle" and "last" actually exist, or this might cause a TypeError.