JavaScript: "Syntax error missing } after function body"

You're missing a semi-colon:

function ToServer(cmd, data) {
    var xmlObj = new XMLHttpRequest();
    xmlObj.open('POST', 'handler.php', true);
    xmlObj.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    xmlObj.send(cmd + data);
    xmlObj.onreadystatechange = function() {
        if(xmlObj.readyState === 4 && xmlObj.status === 200) {
            if(cmd == 'cmd=push') {
                document.getElementById('pushResponse').innerHTML = xmlObj.responseText;
            }
            if(cmd == 'cmd=pop') {
                document.getElementById('messages').innerHTML += xmlObj.responseText;
            }
            if(cmd == 'cmd=login') {
                if(xmlObj.responseText == 'OK') {
                    self.location = 'index.php';
                }
                else {
                    document.getElementById('response').innerHTML = xmlObj.responseText;
                }
            }           
        }
    }; //<-- Love the semi
}

Additional missing semi-colon:

// Start checking of messages every second
window.onload = function() {
    if (getUrlVars()['to'] != null) {
        setInterval(GetMessages(), 1000);
    }
}; //<-- Love this semi too!

I think you can adapt divide and conquer methodology here. Remove last half of your script and see whether the error is coming. If not, remove the first portion and see. This is a technique which I follow when I get an issue like this. Once you find the half with the error then subdivide that half further till you pin point the location of the error.

This will help us to identify the actual point of error.

I do not see any problem with this script.

This may not be the exact solution you want, but it is a way to locate and fix your problem.

It looks like it's being interpreted as being all on one line. See the same results in Fiddler 2.

This problem could do due to your JavaScript code having comments being minified. If so and you want to keep your comments, then try changing your comments - for example, from this:

// Reset the input box

...to...

/* Reset the input box */

Adding a note: very strangely this error was there very randomly, with everything working fine.

Syntax error missing } after function body | At line 0 of index.html

It appears that I use /**/ and //🜛 with some fancy Unicode character in different parts of my scripts for different comments.

This is useful to me, for clarity and for parsing.

But if this Unicode character and probably some others are used on a JavaScript file in comments before any JavaScript execution, the error was spawning randomly.

This might be linked to the fact that JavaScript files aren't UTF-8 before being called and read by the parent page. It is UTF-8 when the DOM is ready. I can't tell.

It seems there should be added another semicolon in the following code too:

// Start checking of messages every second
window.onload = function() {
    if(getUrlVars()['to'] != null) {
        setInterval(GetMessages(), 1000);
    }
};  <---- Semicolon added

Also here in this code, define the var top of the function

function readCookie(name) {
    var i;
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}

"Hm I think I found a clue... I'm using Notepad++ and have until recently used my cPanel file manager to upload my files. Everything was fine until I used FireZilla FTP client. I'm assuming the FTP client is changing the format or encoding of my JS and PHP files. – "

I believe this was your problem (you probably solved it already). I just tried a different FTP client after running into this stupid bug, and it worked flawlessly. I'm assuming the code I used (which was written by a different developer) also is not closing the comments correctly as well.