web-scraping from a website that does not change URL

I am very new to web-scraping, and I am having some difficulty scraping this website's content. I basic would like to collect the pesticide name and active ingredient, but the URL does not change, and I could not find a way to click the grids. Any help?

library(RSelenium)
library(rvest)
library(tidyverse)

rD <- rsDriver(browser="firefox", port=4547L, verbose=F)
remDr <- rD[["client"]]

remDr$navigate("http://www.cdms.net/Label-Database")

Solution

This site calls an API to get the list of manufacturers: http://www.cdms.net/labelssds/Home/ManList?Keys=

On the products page, it also uses another API with the manufacturer ID, for example: http://www.cdms.net/labelssds/Home/ProductList?manId=537

You just need to loop through the Lst array and append the result to a dataframe. For instance, the following code get all the products for the first 5 manufacturers :

library(httr)

manufacturers <- content(GET("http://www.cdms.net/labelssds/Home/ManList?Keys="), as = "parsed", type = "application/json")
maxManufacturer <- 5

index <- 1
manufacturerCount <- 0
data = list()

for(m in manufacturers$Lst){
  print(m$label)
  productUrl <- modify_url("http://www.cdms.net/labelssds/Home/ProductList", 
    query = list(
      "manId" = m$value
    )
  )
  products <- content(GET(productUrl), as = "parsed", type = "application/json")

  for(p in products$Lst){
    data[[index]] = p
    index <- index + 1
  }

  manufacturerCount <- manufacturerCount + 1
  if (manufacturerCount == maxManufacturer){
    break
  }
  Sys.sleep(0.500) #add delay for scraping
}

df <- do.call(rbind, data)
options(width = 1200)
print(df)