How to get a DOM element's ::before content with JavaScript?

Question

I want to know whether it is possible to get a DOM element\'s ::before content, which was set by CSS3.

I have tried some ways, but I still can\'t make it, s

Answer 1

Pass ":before" as the second parameter to window.getComputedStyle():

console.log(getComputedStyle(document.querySelector('p'), ':before').getPropertyValue('content'));

p::before,
p::after {
  content: ' Test ';
}

<p>Lorem Ipsum</p>

Answer 2

getComputedStyle() & getPropertyValue()

getComputedStyle(document.querySelector('span.search-box'), '::after').getPropertyValue('content');