Display an HTML form via Javascript document.write?

I'd propose a slightly different approach.

Use JavaScript to create the HTML form and include that script into all other websites using the same source.

Assume form.js is the file you want to include in every website.

Live DEMO

forms.js

var company = {};// Avoid name clashes!!!

company.form = function() {
    this.render();
};

company.form.prototype.render = function() {
    var url = "blablabla";
    this.form = document.createElement("form");
    this.form.setAttribute("method", "post");
    this.form.setAttribute("name", "company-specialform");
    this.form.setAttribute("action", url);

    var input = document.createElement("input");
    input.setAttribute("type", "text");
    input.setAttribute("value", "test");

    var submit = document.createElement("input");
    submit.setAttribute("type", "submit");
    submit.setAttribute("value", "submit");
    this.form.appendChild(input);
    this.form.appendChild(submit);
    var that = this;
    this.form.onsubmit = function(event) {
        that.submit.call(that, event);
    };
};

company.form.prototype.submit = function(event) {
    event.preventDefault(); // if needed
    alert(" Custom submit was called");
};

company.form.prototype.getForm = function() {
    return this.form;
};

company.form.append = function(container) {
    var form = new company.form();
    container.appendChild(form.getForm());
};

var target = document.getElementById("container");

company.form.append(target);

Now simply include forms.js on any other website, but make sure you use the same src for all of those websites, so you can keep the script up to date.

Now on every of those website, they can add the form with company.form.append(someDiv) and when you update the script the update will be available on all websites.

You can use simple jQuery:

<script>
$('body').load(url);
</script>

well, a <script> tag is for including javascript, not HTML. You want to look into ajax. You want to load the html file via ajax into a div.

Alternatively, leave it as an iframe. Iframes are for including one page into another.

Edit The example you included from the affiliate is meaningless for you. They are loading javascript that is generated programmatically from a PHP server side script based on input from client side cookies. You are trying to load en external html file, these are two different tasks.

javascript in your HEAD tag

<!-- Include the jquery library - never re-create the wheal -->
<script type='text/javascript' src='http://code.jquery.com/jquery-1.9.1.min.js'></script>
<script type='text/javascript'>
$(document).ready(function() {
    // Run once the page is loaded
    $('#putFormHere').load('http://www.maxcashtitleloans.com/lmapp.html');
});
</script>

Replace your current iframe with this

<div id='putFormHere'></div>

Assumption

I'm assuming that www.maxcashtitleloans.com is the same domain as your current page. If not then they only way to do this is via an iframe. Javascript will not support cross-site scripting.

Script tags do not HTML rendering. You have to add HTML render to your html page. Maybe you can add this code to your html page. This code render your html codes on javascript.

document.write($(body).html());