Detailed documentaion on computerVisionClient.read() (In JavaScript)

I am working on a project where I need to take a picture with a camera and then use that image to call the computerVision API for OCR. In the documentation, it mentions that you can use an image URL or an absolute path to a file. Are there other param options for "computerVisionClient.read(URL)." One option that I would like to do is pass the image as a base64 string but I do not see documentation about how to do this.

edit: i can only really find examples of using the URL passed through the the API. In the documentation is says to use

// To recognize text in a local image, replace client.read() with readTextInStream() as shown:

but when i try taht it just says that readTextInStream() is not a function

i am trying to convert a base64 string to binary then pass it to the API since the documentations says that you can do that but for some reason there are no examples and no documentaion that i can find that works for this use case.