WordPress function to tell if you're on a blog page, current page is a blog page

is_blog

<?php

/**
 * Are we on a blog page?
 *
 * @return bool
 **/
function is_blog()
{
  return (is_post_type_archive('post') || is_author() || is_category() || is_home() || is_singular('post') || is_tag()) ? true : false ;
}