How does one query the value of a known "class" or "id" on a web link using javascript?

As an example let's use a Google search of the price of bitcoin ... https://www.google.com/search?q=bitcoin+price&rlz=1C1CHBF_enCA867CA867&oq=bitcoin&aqs=chrome.0.35i39j69i57j35i39j0i67j0i67i433j0i67i131i433j0i67l3j0i67i131i433.1157j1j4&sourceid=chrome&ie=UTF-8

So at this link, I know the span element with class "pclqee" contains the value of Bitcoin.

Question is how would I go about asking the value of this with javascript from a webpage of my own making?

Or even another language if you prefer, just looking for methods to query values using web links, thanks.