Question

I was using the following code to detect all the javadoc comments in the pre elements to replace them with a color of my choice.

<script type="text/javascript">
    var arr = document.getElementsByTagName("pre");
    for (var i=0; i<arr.length; i++){
        arr[i].innerHTML = arr[i].innerHTML.replace(/\t/g, '&nbsp;&nbsp;&nbsp;&nbsp;');
        arr[i].innerHTML = arr[i].innerHTML.replace(/</g, '&lt;');
        arr[i].innerHTML = arr[i].innerHTML.replace(/>/g, '&gt;');
        arr[i].innerHTML = arr[i].innerHTML.replace(/\\/*\*\*([^\*]|\*(?!/))*\\*/g, '<font color="#3F5FBF">' + $& + '</font>');
    }
</script>

but it gives me the following error.

Uncaught SyntaxError: Unexpected token ILLEGAL 

EDIT: changed the code to

<script type="text/javascript">
var arr = document.getElementsByTagName("pre");
for (var i=0; i<arr.length; i++){
    arr[i].innerHTML = arr[i].innerHTML.replace(/\t/g, '&nbsp;&nbsp;&nbsp;&nbsp;');
    arr[i].innerHTML = arr[i].innerHTML.replace(/</g, '&lt;');
    arr[i].innerHTML = arr[i].innerHTML.replace(/>/g, '&gt;');
    var reg = /\\\/*\*\*([^\*]|\*(?!\/))*\\*/;
    var cds = arr[i].innerHTML.match(reg);
    for (var j=0; j<cds.length; j++){
        arr[i].innerHTML = arr[i].innerHTML.replace(cds[j], '<font color="#3F5FBF">' + cds[j] + '</font>'); 
    }
}
prettyPrint();
</script>

But the error changes to

Uncaught TypeError: Cannot read property 'length' of null start-ahead.html:234

(anonymous function)

Answer 1

The problem is here /\\/*\*\*([^\*]|\*(?!/))*\\*/g, when you used the \\ and then used /. The program understands that your regex is like this /\\/ and what comes after results in an error. Try this regex:

/\/*\*\*([^\*]|\*(?!\/))*\\*/g

Or, depending on what you want:

/\\\/*\*\*([^\*]|\*(?!\/))*\\*/g