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scrollfix

JQuery辅助文本框在浏览器中固定位置，不随浏览器滚动条滚动

当前为 2019-08-20 提交的版本，查看 最新版本。

此脚本不应直接安装。它是供其他脚本使用的外部库，要使用该库请加入元指令 // @require https://update.cn-greasyfork.org/scripts/388372/726657/scrollfix.js 

  1. // ==UserScript==
  2. // @name         scrollfix
  3. // @version      0.0.1
  4. // @namespace    tsharp.js
  5. // @description  JQuery辅助文本框在浏览器中固定位置，不随浏览器滚动条滚动
  6. // @author       jimbo
  7. // @license      GPLv3
  8. // @match        *
  9. // @icon         none
  10. // @require      http://code.jquery.com/jquery-3.4.1.min.js
  11. // ==/UserScript==
  12.  ; (function ($) {
  13.         jQuery.fn.scrollFix = function (height, dir) {
  14.             height = height || 0;
  15.             height = height == "top" ? 0 : height;
  16.             return this.each(function () {
  17.                 if (height == "bottom") {
  18.                     height = document.documentElement.clientHeight - this.scrollHeight;
  19.                 } else if (height < 0) {
  20.                     height = document.documentElement.clientHeight - this.scrollHeight + height;
  21.                 }
  22.                 var that = $(this),
  23.                     oldHeight = false,
  24.                     p, r, l = that.offset().left;
  25.                 dir = dir == "bottom" ? dir : "top"; //默认滚动方向向下
  26.                 if (window.XMLHttpRequest) { //非ie6用fixed
  27.                     function getHeight() { //>=0表示上面的滚动高度大于等于目标高度
  28.                         return (document.documentElement.scrollTop || document.body.scrollTop) + height - that.offset().top;
  29.                     }
  30.                     $(window).scroll(function () {
  31.                         if (oldHeight === false) {
  32.                             if ((getHeight() >= 0 && dir == "top") || (getHeight() <= 0 && dir == "bottom")) {
  33.                                 oldHeight = that.offset().top - height;
  34.                                 that.css({
  35.                                     position: "fixed",
  36.                                     top: height,
  37.                                     left: l
  38.                                 });
  39.                             }
  40.                         } else {
  41.                             if (dir == "top" && (document.documentElement.scrollTop || document.body.scrollTop) < oldHeight) {
  42.                                 that.css({
  43.                                     position: "fixed"
  44.                                 });
  45.                                 oldHeight = false;
  46.                             } else if (dir == "bottom" && (document.documentElement.scrollTop || document.body.scrollTop) > oldHeight) {
  47.                                 that.css({
  48.                                     position: "fixed"
  49.                                 });
  50.                                 oldHeight = false;
  51.                             }
  52.                         }
  53.                     });
  54.                 } else { //for ie6
  55.                     $(window).scroll(function () {
  56.                         if (oldHeight === false) { //恢复前只执行一次，减少reflow
  57.                             if ((getHeight() >= 0 && dir == "top") || (getHeight() <= 0 && dir == "bottom")) {
  58.                                 oldHeight = that.offset().top - height;
  59.                                 r = document.createElement("span");
  60.                                 p = that[0].parentNode;
  61.                                 p.replaceChild(r, that[0]);
  62.                                 document.body.appendChild(that[0]);
  63.                                 that[0].style.position = "absolute";
  64.                             }
  65.                         } else if ((dir == "top" && (document.documentElement.scrollTop || document.body.scrollTop) < oldHeight) || (dir == "bottom" && (document.documentElement.scrollTop || document.body.scrollTop) > oldHeight)) { //结束
  66.                             that[0].style.position = "absolute";
  67.                             p.replaceChild(that[0], r);
  68.                             r = null;
  69.                             oldHeight = false;
  70.                         } else { //滚动
  71.                             that.css({
  72.                                 left: l,
  73.                                 top: height + document.documentElement.scrollTop
  74.                             })
  75.                         }
  76.                     });
  77.                 }
  78.             });
  79.         };
  80.     })(jQuery);