On the search results page, clicking on the PDF icon will jump you straight to PDF view.
Per
// ==UserScript==
// @name Alldatasheet.com: Single-click PDF access
// @description On the search results page, clicking on the PDF icon will jump you straight to PDF view.
// @namespace giferrari.net
// @include http://www.alldatasheet.com/view.jsp*
// @version 1
// @grant none
// @require http://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.js
// ==/UserScript==
// Grab all links that appear to redirect to a PDF page.
// There isn't a class that we can key off of, so we look for all
// anchors that have a PDF icon in them.
var datasheetPdfLinks = $('img[src="http://other.alldatasheet.com/etc/electronic_parts_datasheet.gif"]').closest('a');
// Open in same window instead of a new one.
datasheetPdfLinks.attr('target', null)
// Go to the PDF page directly.
datasheetPdfLinks.attr('href', function(i, oldHref) {
// From:
// http://www.alldatasheet.com/datasheet-pdf/pdf/317775/COMSET/2N2222.html
// To:
//http://pdf1.alldatasheet.com/datasheet-pdf/view/317775/COMSET/2N2222.html
return oldHref
.replace(/^http:\/\/www.alldatasheet.com/, 'http://pdf1.alldatasheet.com')
.replace(/\/pdf\//, '/view/');
});