Exclude term on Google (Firefox only)

Easily exclude terms from your query using the right-click context menu. v0.9.0 2015-12-20

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name        Exclude term on Google (Firefox only)
// @author      Jefferson "jscher2000" Scher
// @namespace   JeffersonScher
// @copyright   Copyright 2015 Jefferson Scher
// @license     BSD 3-clause
// @description Easily exclude terms from your query using the right-click context menu. v0.9.0 2015-12-20
// @include     http*://www.google.*/*
// @include     http*://encrypted.google.*/*
// @version     0.9.0
// @grant       none
// ==/UserScript==
// DISCLAIMER:     Use at your own risk. Functionality and harmlessness cannot be guaranteed.

var ETGtext = "";

// Context menu options -- Firefox only; do not replace any existing menu!
if (!document.body.hasAttribute("contextmenu") && "contextMenu" in document.documentElement){
  var cmenu = document.createElement("menu");
  cmenu.id = "ETGcontext";
  cmenu.setAttribute("type", "context");
  cmenu.innerHTML = '<menuitem id="ETGexTerm" label="Exclude term(s)"></menuitem>' + 
    '<menuitem id="ETGexPhrase" label="Exclude phrase" disable="disable"></menuitem>';
  document.body.appendChild(cmenu);
  document.getElementById("ETGexTerm").addEventListener("click", ETG_doExclude, false);
  document.getElementById("ETGexPhrase").addEventListener("click", ETG_doExclude, false);
  // attach menu and create event for filtering
  document.body.setAttribute("contextmenu", "ETGcontext");
  document.body.addEventListener("contextmenu", ETG_cmenuFilter, false);
}
function ETG_cmenuFilter(e){
  var s = window.getSelection();
  if (s.isCollapsed){
    ETGtext = ETG_getWord(e.rangeParent, e.rangeOffset);
    document.getElementById("ETGexPhrase").setAttribute("disabled","disabled");
  } else {
    ETGtext = s.getRangeAt(0).toString().trim();
    if (ETGtext.indexOf(" ") > -1) document.getElementById("ETGexPhrase").removeAttribute("disabled");
  }
}
function ETG_getWord(rnode, rstart){
  var txtFull = rnode.textContent;
  var startPos = rstart, endOffset = 1;
  // Expand to the left of the click point
  while(startPos > 0 && txtFull.substr(startPos, endOffset).indexOf(' ') != 0) {
    startPos = startPos - 1;
    endOffset += 1;
  }
  if (txtFull.substr(startPos, endOffset).indexOf(' ') == 0) {
    startPos = startPos + 1;
    endOffset = endOffset - 1;
  }
  // Expand to the right of the click point
  while(startPos + endOffset + 1 < txtFull.length && txtFull.substr(startPos, endOffset).indexOf(' ') == -1) {
    endOffset = endOffset + 1;
  }
  return txtFull.substr(startPos, endOffset).toString().trim();
}
function ETG_doExclude(e){
  if (e.target.id == "ETGexPhrase"){
    var ss = '+-"' + ETGtext.replace(/\s+/g, '+') + '"';
    ETG_reQry(ss, true);
  } else {
    var ss = '+-' + ETGtext.replace(/\s+/g, '+-');
    ETG_reQry(ss, true);    
  }
}

// query modification borrowed from "Google site: Tool (Site results / Exclude sites)"
function ETG_reQry(d, go){
  // compute new URL
  if (!d) return;
  var cancel = false;
  var qa = window.location.href.substr(window.location.href.indexOf("?")+1).split("&");
  var updated = false;
  for (var j=qa.length-1; j>=0; j--){
    if (updated == false){
      if (qa[j].split("=")[0] == "q"){
        if (qa[j].indexOf(d) > -1 || qa[j].indexOf(d.replace(":", "%3A")) > -1) cancel = true;
        else var ipq = qa[j];
        qa[j] += d;
        updated = true;
        var substqry = qa[j];
      } else {
        if (qa[j].indexOf("#q=") > -1){
          if (qa[j].indexOf(d) > -1 || qa[j].indexOf(d.replace(":", "%3A")) > -1) cancel = true;
          else var ipq = qa[j].substr(qa[j].indexOf("#q=")+1);
          qa[j] += d;
          updated = true;
          var substqry = qa[j].substr(qa[j].indexOf("#q=")+1);
        }
      }
    } else {
      if (qa[j].split("=")[0] == "q"){
        if (go) qa[j] = ipq;
        else qa[j] = substqry;
      } else {
        if (qa[j].indexOf("#q=") > -1){
          if (go) qa[j] = qa[j].substr(0, qa[j].indexOf("#q=")+1) + ipq;
          else qa[j] = qa[j].substr(0, qa[j].indexOf("#q=")+1) + substqry;
        }
      }
    }
  }
  if (cancel != true) var locnew = window.location.href.substr(0, window.location.href.indexOf("?")+1) + qa.join("&");
  else locnew = "cancel";
  if (go) window.location.href = locnew;
  else return locnew;
}