Remove all HTML tags from a html body except <a>, <br>, <b> and <img>

问题

When reading some email HTML body, I often have lots of HTML tags, that I don't want anymore.

How to remove from a string, in Javascript, all HTML tags like:

<anything ...>

or

</anything>

except these few cases <x ...>, </x>, <x ... /> for x being:

• a
• br
• b
• img

I thought about something like:

s.replace(/<[^a].*>/g, '');

but I'm not sure how to do it.

Example:

<div id="hello">Hello</div><a href="test">Youhou</a>` 

should become

Hello<a href="test">Youhou</a>

Note: I'm looking for a few lines-of-code solution that would work for 90% of the times (the email body comes from my own emails, so I didn't include anything malicious), not for a full solution that would require third-party tool/library.

回答1:

Try replacing

<\/?(?!(a|br|b|img)\b)\w+[^>]*>

with nothing.

<\/? Match the start <, optionally followed by a /

(?!(a|br|b|img)\b) Negative look-ahead ensuring we don't match a, br, b or img tags.

\w+[^>]*> Match the rest of the tag.

Here at regex101.

回答2:

This isn't very beautiful but should meet your requirements

html.replace(/<\/?([^\s>])[^>]*>/gi,function(tag,tagName){
    return ['a','b','br','img'].indexOf(tagName.toLowerCase()) >= 0? tag: '';
})

\/? optional slash ([^\s>]) match tagname [^>]* attributs spaces ect

回答3:

You can pass a function as a second parameter to .replace, that will decide what to do with the output.

str.replace(/<[^a].*>/g, function (s) { /* do something with s */ });

See MDN documentation on replace:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace

来源：https://stackoverflow.com/questions/46466814/remove-all-html-tags-from-a-html-body-except-a-br-b-and-img