Client Side, Save Contents Of Form On New Line In .txt File?

On a client side HTML form, on hitting submit, I would like the data entered in the the form to be saved on the next available line within a .txt file.

For example, a basic HTML Form filled in as follows:

Name: Haze
Age: 400
Info: Hello World!

... on clicking 'Submit', the information would be saved to 'form.txt' on a new line, simply seperated by commas would be fine, example:

Haze, 400, Hello World!

If possible, the date and time the info was saved would really be great as well, example:

01/01/2010 9:41: Haze, 400, Hello World!

I might I cannot find anything on the internet for doing this client side.