$ cat log
./testing/file.pdf
./sample.jpg
./example.html
./testcondition.css

$ echo 'gfdg' >example.html

$ cat example.html
gfdg

$ cat test
#!/bin/bash

SEARCH_IN_FILES="html htm css js"
declare -A MYMAP=( [abc]=test1 [efg]=test2 [gfdg]=test3 )

while read line;do

    if grep -w "${line##*.}" <<<$SEARCH_IN_FILES >/dev/null; then
        
        for i in "${!MYMAP[@]}";do
               sed -i 's/'"$i"'/'"${MYMAP[$i]}"'/g' $line
        done
    fi

done <"log"

$ bash test

$ cat example.html
test3