Using JavaScript to dynamically create HTML on page load

Question

Here is a very brief background of what I want to do. I need to create a very small block of JavaScript that will be given to many websites to embed in their home pages. Then, when visitors hit those home pages, a URL will automatically get called that collects certain statistics and returns a small image. I have some of this in place already as follows:

        <script>
            /* Determine if there is a cookie already exists and get its value if not. */
            var userId;
            match = document.cookie.match(new RegExp("someUserId" + '=([^;]+)'));
            if (match)
                userId = match[1];
            else {
                /* generate a random 10 character string */
                userId = (Math.random() + 1).toString(36).substring(5, 15);

                /* Store this as a cookie value */
                <needs to be done>
            }

            /* This is what I need help with. A page is called when the home page loads to collect some stats and return a small image */
            <a href="http://www.SomeAnalysisSite.com/"><img src="http://www.SomeAnalysisSite.com/Log/?Id=1@userId=xxx" alt=""/></a>
        </script>

The piece I don't know how to do is the very last line (with the img tag). I need to generate this dynamically and inserted into the DOM (I think), after the value of "userId" is generated so it can be included as a query parameter in the img src URL. Or perhaps there is a better way? Of course, I'll minify this before it's sent to third party websites.

sujit · Accepted Answer · 2016-01-09 13:34:25Z

3

Replace last line with:

document.write('<a href="http://www.SomeAnalysisSite.com/"><img src="http://www.SomeAnalysisSite.com/Log/?Id=1@userId=' + userId + '" alt=""/></a>');

And check if you mean to put & in place of @ in the above line.

answered Jan 9, 2016 at 13:34

sujit

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Comments

puemos · Accepted Answer · 2016-01-09 14:11:39Z

0

generate a userId;
create the url with the new userId;
create a new img element: document.createElement('img');
insert a new src attribute img.setAttribute('src', imgUrl);
create a new a element: document.createElement('a');
insert a new href attribute link.setAttribute('href', linkUrl);
insert the "img" inside the "a" link.appendChild(img);
insert the "a" Element to the dom inside the "somediv" element

var userId;

/*1*/
userId = (Math.random() + 1).toString(36).substring(5, 15);
var siteUrl = "http://www.SomeAnalysisSite.com/" 
/*2*/
var imgUrl = siteUrl + "Log/?Id=1@userId=" + userId;
var linkUrl = siteUrl;
/*3*/
var img = document.createElement('img');
/*4*/
img.setAttribute('src', imgUrl);
/*5*/
var link = document.createElement('a');
/*6*/
link.setAttribute('href', linkUrl);
/*7*/
link.appendChild(img);
/*8*/
document.getElementById("somediv").appendChild(link);

<html>

<body>
  
  <div id="somediv">
</body>

<script>
</script>

</html>

edited Jan 9, 2016 at 14:11

answered Jan 9, 2016 at 13:38

puemos

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1 Comment

Ferrybig Over a year ago

While a code may solve the problem, it isn't very useful in understanding the problem, can you explain what you did and how the newly added code solves the original problem.

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