Add upload field to a form and validate via JS

I need to add an upload photo button to an already created form that works both online and offline. How is the form working up to now? When the user fills up the form saves the data is saved into a google spreadsheet and also sends an email confirming that a new message was sent. What do I need? I need a new field created with upload option. Example: <input type="file"> The form should validate this new field to make sure only JPEG and PNG are uploaded, with a certain limit of maximum size The photo then gets saved and a link to the photo is shown on the Google Drive. - The upload field should be hidden, only if the user selects from the radio button: Do you want to upload a photo? YES / NO If the user selects YES then the field is shown and validated if the user selects NO then the field in not shown and is not mandatory.