Check if a file exists in a linux script

Question

i made a linux script which receives as first argument a path to a directory. I don't know the path. And i want to check if "file.txt" exists at that certain path . For example :

if [ -e $1/file.txt ];then
       echo HAHA
fi

Solution

if [[ -e "$1/file.txt" ]]; then
       echo "It exists"
fi