I try to use opencv.js 'https://docs.opencv.org/3.4/d5/d10/tutorial_js_root.html) with call to
cv.estimateAffine2D( srcArray, dstArray)

First, where can I find the help on calling prototype in JS. It is difficult to find correspondance between prototype in C++ and in JS.

Second, estimateAffine2D accepts argument as InputArray and OutputArray.What is the correspondance in openjs ? (I don't find them when I use assistance (in visual studio code) during debug (I input cv.xxx to get the list of functions or types))
And How can I create such type ?

Do you have a small sample of usage ?

Best regards.