How do I get the information from a meta tag with JavaScript?

Question

The other answers should probably do the trick, but this one is simpler and does not require jQuery:

document.head.querySelector("[property~=video][content]").content;

The original question used an RDFa tag with a property="" attribute. For the normal HTML <meta name="" …> tags you could use something like:

document.querySelector('meta[name="description"]').content

You can use this:

function getMeta(metaName) {
  const metas = document.getElementsByTagName('meta');

  for (let i = 0; i < metas.length; i++) {
    if (metas[i].getAttribute('name') === metaName) {
      return metas[i].getAttribute('content');
    }
  }

  return '';
}

console.log(getMeta('video'));

One liner here

document.querySelector("meta[property='og:image']").getAttribute("content");

There is an easier way:

document.getElementsByName('name of metatag')[0].getAttribute('content')

function getMetaContentByName(name,content){
   var content = (content==null)?'content':content;
   return document.querySelector("meta[name='"+name+"']").getAttribute(content);
}

Used in this way:

getMetaContentByName("video");

The example on this page:

getMetaContentByName("twitter:domain");

If you use JQuery, you can use:

$("meta[property='video']").attr('content');