Invisible Delimiter for Strings in HTML

问题

I need a way to identify certain strings in HTML markup. I know what the strings are, but it is possible that they could be substrings of other strings in the document. To find them, I output a special delimiter character (currently using \032). On page load, we go through the HTML and record the location of the strings, and remove the delimiter.

Unfortunately, most browsers show the delimiter character until we can find and remove them all. I'd like to avoid that if possible. Is there a character or string that will be preserved in the HTML content (so a comment wont work) but wont be visible to the user? It also needs to be something that is fairly unlikely to appear next to a string, so something like   wouldn't work either.

EDIT: Sorry, I forgot to mention that the strings will be in attributes, so any sort of tag wont work.

回答1:

&zwnj; - zero-width non-joiner (see http://htmlhelp.org/reference/html40/entities/special.html)

On the off chance that this already appears in your text, double it up (eg: &zwnj;&zwnj;mytext&zwnj;&zwnj;

Edit in response to comment: works in Firefox 3. Note that you have to search for the Unicode value of the entity.

<html>
<body>
    <div id="test">
        This is a &zwnj;test
    </div>

    <script type="application/javascript">
        var myDiv = document.getElementById("test");
        var content = myDiv.innerHTML;
        var pos = content.indexOf("\u200C");
        alert(pos);
    </script>
</body>
</html>

回答2:

You could insert them into <span> elements. This will work only for in-page text (not attributes, or the like).

Otherwise, you could insert a whitespace character that your program doesn't already output as part of the HTML, like a tab character (\x09), a vertical tab (\x0b), a bare carriage return (\x0d) — without a newline beside it, ala Windows text encoding — or, just a null byte (\x00).

回答3:

The best thing that I shall like to insert, which is not visible on the browser, will be a pair of tags with some special id, like <span id="delimiter" class="Delimiter"></span>. This will not show up on the content, while this can be present in the doc. You don't need to remove them.

回答4:

You could use left-to-right (LTR) marks. Is this for some sort of XSS testing? If so, this might be of interest: Taint support for PHP

来源：https://stackoverflow.com/questions/2812253/invisible-delimiter-for-strings-in-html

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html

non-printing-characters