It is possible to validate within a multiple Input file that one of the files is of type word (.doc, .docx) and another of type PDF (.pdf)?
I have a created a working codepen that shows you a javascript code which iterates over the files uploaded with the file upload input, and checks if their file extension is in pdf, doc or docx.
Though as others have mentioned in comments, checking file format in client-side is unsafe and you should double check on the server side.
Snippet below
function testFiles(){
var fileInput = document.getElementById('upload');
// iterate over files
for (let i = 0; i < fileInput.files.length; i++) {
var filename = fileInput.files[i].name
// get file extension
var file_extension = filename.split('.').pop()
if(file_extension == "pdf"
|| file_extension == "doc"
|| file_extension == "docx"){
alert(filename + ' is a .pdf, .doc or .docx file')
}
else alert(filename + ' is not an authorized file')
}
} <input id="upload" type="file" onchange="testFiles()" multiple>