javascript - Website changes my link target: how do I change it back? -

i'm using instructure canvas—a learning management system—to code web page. can use javascript has in external file, not embedded in html.

i want have few buttons linking videos show in iframe on current page so:

<a class="iframelink" href="https://player.vimeo.com/video/90612" target="vimeobox">watch</a> 

the problem learning management system changes links pop in external tab so:

<a class="external" target="_blank" href="https://player.vimeo.com/video/90612">watch</a> 

is there way prevent this?

after learning management system has generated video links, run following javascript function:

function changelinks() {    var links = document.getelementsbytagname('a');    (var = 0; < links.length; ++i) {      var link = links[i];      if (link.classname == 'external') {        link.classname = 'iframelink';        link.target = 'vimeobox';      }    }  }    changelinks();

<a class="external" target="_blank" href="https://player.vimeo.com/video/90612">watch</a>

this script takes anchor tags on page have class="external" , modifies them changing class , target.