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<input type="file" id="test" name="test" accept="application/pdf"/>
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<input #fileInput type="file" id="avatar" accept="application/pdf,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document" />
application/pdf means .pdf
application/msword means .doc
application/vnd.openxmlformats-officedocument.wordprocessingml.document means .docx
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application/msword, application/vnd.openxmlformats-officedocument.wordprocessingml.document, application/vnd.ms-powerpoint, application/vnd.openxmlformats-officedocument.presentationml.slideshow, application/vnd.openxmlformats-officedocument.presentationml.presentation