skip classes with no students before scraping process

scrape.js

@@ -97,14 +97,25 @@ const scrapeInstance = async (link, page) => {
 	const instanceLinks = await page.$$('tr td:nth-child(2) a');
 
 	for(instance of instanceLinks){
-		
+		const td = await instance.getProperty('parentNode');
+		const tr = await td.getProperty('parentNode');
+		const sibling = await tr.$('.numeric');
+		const siblingHTML = await sibling.getProperty('innerHTML');
+		const numStudents = parseInt(await siblingHTML.jsonValue());
+		if(numStudents > 0){
 			const linkHTML = await instance.getProperty('href');
 			const href = await linkHTML.jsonValue()
 			const instanceID = href.match(/[0-9]*$/)[0];
 			const res = await client.query(`SELECT * FROM instances WHERE instance_id = ${instanceID}`);
 			if(res.rowCount === 0){
 				await scrapeInstance(instance, page);
+			} else {
+				console.log(instanceID, 'found');
+			}
+		} else {
+			console.log('no students, skipping');
 		}
+		
 	}
 
 	console.log('done');