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Using regular expressions to find img tags without an alt attribute

I am going through a large website (1600+ pages) to make it pass Priority 1 W3C WAI. As a result, things like image tags need to have alt attributes.

What would be the regular expression for finding img tags without alt attributes? If possible, with a wee explanation so I can use to find other issues.

I am in an office with Visual Web Developer 2008. The Edit >> Find dialogue can use regular expressions.

Solution

  • This is really tricky, because regular expressions are mostly about matching something that is there. With look-around trickery, you can do things like 'find A that is not preceded/followed by B', etc. But I think the most pragmatic solution for you wouldn't be that.

    My proposal relies a little bit on your existing code not doing too crazy things, and you might have to fine-tune it, but I think it's a good shot, if you really want to use a RegEx-search for your problem.

    So what I suggest would be to find all img tags, that can (but don't need to) have all valid attributes for an img-element. Whether that is an approach you can work with is for you to decide.

    Proposal:

    /<img\s*((src|align|border|height|hspace|ismap|longdesc|usemap|vspace|width|class|dir|lang|style|title|id)="[^"]"\s*)*\s*\/?>/

    The current limitations are:

    1. It expects your attribute values to be delimited by double quotes,
    2. It doesn't take into account possible inline on*Event attributes,
    3. It doesn't find img elements with 'illegal' attributes.