How can I detect the current tab's mime type in a Google Chrome extension?

Question

I want to see if the current tab is a PDF file from a background page.

I can check the url for .pdf at the end but there are some PDF files that don\'t have that.

Answer 1

You can evaluate the property document.contentType on the current tab. Here is an example on browserAction :

chrome.browserAction.onClicked.addListener(() => {
    chrome.tabs.getSelected((tab) => {
        chrome.tabs.executeScript(tab.id, { code: 'document.contentType' }, ([ mimeType ]) => {
            alert(mimeType);
        });
    })
});

This property returns the MIME type that the document is being rendered as, not the Content-Type header (no information about the charset).