Javascript: Save json data as a file on the server / user's hard disk.

Question

I have developed an app that allows the user to fill out text fields with information. I want them to be able to press a button that will make a file with data (a really long array with info on what they typed and where it should go) so they can reload the data at a later date. I don't have a server now, and I am sending this app as a standalone html app to my friends for their use until I get hosing / mySql / etc. Is there a way that when they click on a button it will take this data (saved as an array, save_data), put it into a file, and basically begin the download process from their web-browser? And later on, what tech would I need to be looking into to save this into online user accounts?

Answer 1

If you don't have a server, then no ... there is no way to initiate a file download/save based on dynamically generated data with javascript

Answer 2

It is posible, but only if you force your users to use windows and microsoft internet explorer. You can send the html file as a hta file, wich can write and read from data from the hard disk. check http://msdn.microsoft.com/en-us/library/ms536496%28VS.85%29.aspx for more information.
An hta file is basically a local html file with some extra tags in the header, and is run (interpreted) locally without security restrictions, like any exe file. I don't know how to show the complete html code here,(markdown is not for me), so if you want an example:
1 - create a file test.hta, with the standard html, head, body and script tags
2 - inside head tag, insert

    <HTA:APPLICATION 
    ID="oMyApp" 
    APPLICATIONNAME="test"  
    BORDER="yes" 
    CAPTION="yes" 
    SHOWINTASKBAR="yes"
    SINGLEINSTANCE="yes" 
    SYSMENU="yes">
 </HTA:APPLICATION>

3 - inside body tab put a button with onclick="writeText();"
4 - inside the script tag insert

    function writeText(){
        try{
            var fso = new ActiveXObject("Scripting.FileSystemObject"); 
            var fileObject = fso.OpenTextFile("C:\\testhta.txt", 8, true,0);        
            fileObject.WriteLine('text file written');
            fileObject.close();
        }catch(ex){
            alert(ex);
        }
    }

5 - save it, doubleclick it, click on the button and you will get a nice "C:\testhta.txt" file with 'text file written' in it.