Okay - so, you are trying to access Airtable data from a third-party system that supports scripting. Unless that system (gyazo.com) provides a way to import the Airtable JavaScript SDK (like you would when developing a NodeJS service), you are faced with the task of building the complete API integration using whatever flavor of JavaScript it supports.
As such, You must use the gyazo platform and whatever scripting features they allow to perform an HTTPS POST request to the Airtable API. To know the exact code to do this would require intimate knowledge of the gyazo platform. Once you are able to make a request into Airtable, you can iterate across the record set to count the number of records in a given table.
Since the gyazo platform supports a public REST API, a more appropriate approach may be to build your Airtable API code in a platform that you control and one in which Airtable’s SDK resources are available to make this easier.
I assume your goal is to pull images from Gyazo into Airtable or to pull images from Airtable for use in Gyazo. If this is correct, you probably need a NodeJS app or possibly a Google Cloud Platform app that can read from Gyazo and write to Airtable.
To be clear - all this is all simply speculation on my part because I don’t really know anything about your project or its objectives.
