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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

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/388372/726659/scrollfix.js 

// ==UserScript==
// @name         scrollfix
// @version      0.0.1
// @namespace    tsharp.js
// @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
// @author       jimbo
// @license      GPLv3
// @match        *
// @icon         none
// @require      http://code.jquery.com/jquery-3.4.1.min.js
// ==/UserScript==
 ; (function ($) {
        jQuery.fn.scrollFix = function (height, dir) {
            height = height || 0;
            height = height == "top" ? 0 : height;
            return this.each(function () {
                if (height == "bottom") {
                    height = document.documentElement.clientHeight - this.scrollHeight;
                } else if (height < 0) {
                    height = document.documentElement.clientHeight - this.scrollHeight + height;
                }
                var that = $(this),
                    oldHeight = false,
                    p, r, l = that.offset().left;
                dir = dir == "bottom" ? dir : "top"; //默认滚动方向向下
                if (window.XMLHttpRequest) { //非ie6用fixed
                    function getHeight() { //>=0表示上面的滚动高度大于等于目标高度
                        return (document.documentElement.scrollTop || document.body.scrollTop) + height - that.offset().top;
                    }
                    $(window).scroll(function () {
                        if (oldHeight === false) {
                            if ((getHeight() >= 0 && dir == "top") || (getHeight() <= 0 && dir == "bottom")) {
                                oldHeight = that.offset().top - height;
                                that.css({
                                    position: "fixed",
                                    top: height,
                                    left: l
                                });
                            }
                        } else {
                            if (dir == "top" && (document.documentElement.scrollTop || document.body.scrollTop) < oldHeight) {
                                that.css({
                                    position: "fixed"
                                });
                                oldHeight = false;
                            } else if (dir == "bottom" && (document.documentElement.scrollTop || document.body.scrollTop) > oldHeight) {
                                that.css({
                                    position: "fixed"
                                });
                                oldHeight = false;
                            }
                        }
                    });
                } else { //for ie6
                    $(window).scroll(function () {
                        if (oldHeight === false) { //恢复前只执行一次，减少reflow
                            if ((getHeight() >= 0 && dir == "top") || (getHeight() <= 0 && dir == "bottom")) {
                                oldHeight = that.offset().top - height;
                                r = document.createElement("span");
                                p = that[0].parentNode;
                                p.replaceChild(r, that[0]);
                                document.body.appendChild(that[0]);
                                that[0].style.position = "absolute";
                            }
                        } else if ((dir == "top" && (document.documentElement.scrollTop || document.body.scrollTop) < oldHeight) || (dir == "bottom" && (document.documentElement.scrollTop || document.body.scrollTop) > oldHeight)) { //结束
                            that[0].style.position = "absolute";
                            p.replaceChild(that[0], r);
                            r = null;
                            oldHeight = false;
                        } else { //滚动
                            that.css({
                                left: l,
                                top: height + document.documentElement.scrollTop
                            })
                        }
                    });
                }
            });
        };
    })(jQuery);