R ifelse condition in row, assign value to new column

I have been looking for a decent answer for quite sometime, in Python a for loop would solved this in a matter of seconds. I have got about 100K URL, I m trying to group them based on a specific string that they contain, I have seen many similar example to mine however nothing is quite what I need. The most popular answer is using a ifelse, which doesn't work in my case as I m using a long list, if there is a "if" option I will take it(as oppose to ifelse)

Reproducible code

list<-c("birthday","anniv")
myData <-data.frame(URL = c("/birthday/promoid:654654","/birthday/products/","/anniversary","/anniversary/?type=gifts","/celebration","/celebration"), PageView=1:6*515)

then I want to create a new column called "occasion", so I can group the URLs and expect the below

myData$occasion<-ifelse(grepl("birthday", myData$URL),"birthday",
                    ifelse(grepl("anniv", myData$URL),"anniv",
                           ifelse(grepl("anniv", myData$URL),"anniv","NA")

                           )
                    )

URL PageView occasion
1 /birthday/promoid:654654      515 birthday
2      /birthday/products/     1030 birthday
3             /anniversary     1545    anniv
4 /anniversary/?type=gifts     2060    anniv
5             /celebration     2575       NA
6             /celebration     3090       NA

Here I have used nested ifelse, however it is unfeasible as the list of keyword will reach 10K I have looked into lapply but haven't succeeded as I have simply no idea how to assign the value to a new column

lapply(list, function(list) 
        sub(paste0(".*",list,".*"),list, myData$URL, ignore.case = TRUE)
)

as this give me a list

myData$Occasion<- lapply(list, function(list) 
        sub(paste0(".*",list,".*"),list, myData$URL, ignore.case = TRUE)
)