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Chrome extension PDF detection with webRequest
'use strict';
/**
* Get the header from the list of headers for a given name.
* @param {Array} headers responseHeaders of webRequest.onHeadersReceived
* @return {undefined|{name: string, value: string}} The header, if found.
*/
function getHeaderFromHeaders(headers, headerName) {
for (var i = 0; i < headers.length; ++i) {
var header = headers[i];
if (header.name.toLowerCase() === headerName) {
return header;
}
}
}
/**
* Check if the request is a PDF file.
* @param {Object} details First argument of the webRequest.onHeadersReceived
* event. The properties "responseHeaders" and "url"
* are read.
* @return {boolean} True if the resource is a PDF file.
*/
function isPdfFile(details) {
var header = getHeaderFromHeaders(details.responseHeaders, 'content-type');
if (header) {
var headerValue = header.value.toLowerCase().split(';', 1)[0].trim();
return (headerValue === 'application/pdf' ||
headerValue === 'application/octet-stream' &&
details.url.toLowerCase().indexOf('.pdf') > 0);
}
}
chrome.webRequest.onHeadersReceived.addListener(
function callback(details) {
if (isPdfFile(details)) {
chrome.browserAction.setBadgeText({text: 'PDF'});
} else {
chrome.browserAction.setBadgeText({text: 'HTML'});
}
},
{urls: ['<all_urls>'], types: ['main_frame']},
['responseHeaders']
);
{
"manifest_version": 2,
"name": "Detecting PDFs with webRequest Demo",
"description": "This extension demonstrates a technique for detecting PDFs with Chrome's webRequest API",
"version": "1.0",
"browser_action": {},
"permissions": [
"webRequest",
"<all_urls>"
],
"background": {
"scripts": ["eventPage.js"],
"persistent": true
}
}
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