如何在 Google Chrome 扩展程序中检测当前选项卡的 MIME 类型? [英] How can I detect the current tab's mime type in a Google Chrome extension?

问题描述

我想查看当前选项卡是否是来自背景页面的 PDF 文件.

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

我可以在最后检查 .pdf 的网址，但有些 PDF 文件没有.

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

推荐答案

您无法使用当前的 Chrome API 来获得它.您可以做的是通过 XHR 再次加载此页面并检查返回内容类型标头.像这样:

You can't get it using current Chrome API afaik. What you can do is load this page again through XHR and check returned content-type header. Something like this:

背景 html:

chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
    if(changeInfo.status == "loading") {
        if(checkIfUrlHasPdfExtension(tab.url)) {
            //.pdf
            pdfDetected(tab);
        } else {
             var xhr = new XMLHttpRequest();
             xhr.open("GET", tab.url, true);
             xhr.onreadystatechange = function() {
               if (xhr.readyState == 4) {
                 var contentType = xhr.getResponseHeader("Content-Type");
                 if(checkIfContentTypeIsPdf(contentType)) {
                    pdfDetected(tab);
                 }
               }
             }
             xhr.send();
        }
    }
});

ma​​nifest.json:

"permissions": [
    "tabs", "http://*/*", "https://*/*"
]

对于 PDF 文件，返回的内容类型应为 application/pdf.但要记住的是，内容类型标头也可以包含编码:text/html;字符集=UTF-8.

For PDF files returned content type should be application/pdf. Something to keep in mind though is that content-type header could contain encoding as well: text/html; charset=UTF-8.

这篇关于如何在 Google Chrome 扩展程序中检测当前选项卡的 MIME 类型?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！