javascript从路径数组中获取文件扩展名

Question

I have a page like below, I want to get all filename extensions into an array, filter them and if is a ppt (or whatever) to append the link for downloading the necessary software after the document link

sample page

 <p><a href="/someurl/file.ppt">Presentation</a>
 <br/>
 <a href="/someurl/file.pdf">Rules</a>
 </p>

desired result

<p><a href="/someurl/file.ppt">Presentation</a>
<br/>
<a href="#">Get the Microsoft® Powerpoint viewer</a>
<br/>
<a href="/someurl/file.pdf">Rules</a>
<br/>
<a href="#">Get Adobe reader</a>
</p>

so far I got here and if I try to apply any filter like 'lastIndexOf' to get the extensions I got error.

var links = document.getElementsByTagName("a");
for (var i = 0; i < links.length; i++)  {
//if(links[i].lastIndexOf('.'))
console.log(links[i].href);
}

Please help, Thank you

I realized that I have some <a> tags inside <li> tag like

<ul>
<li><a href="/someurl/file.ppt">Presentation</a><li>
</ul>

how can I get href from both situations?

Answer 1

You need to get the last index of the href attribute, not on the object.

links[i].href.lastIndexOf('.')

you did it in your console.log