其實滾動監聽使用的情況還是很多的，比如導航居于右側，當主題內容滾動某一塊的時候，右側導航對應的要高亮。
實現功能
1、當滾動區域內設置的hashkey距離頂點到有效位置時，就關聯設置其導航上的指定項
2、導航必須是 .nav > li > a 結構，并且a上href或data-target要綁定hashkey
3、菜單上必須有.nav樣式
4、滾動區域的data-target與導航父級Id（一定是父級）要一致。
<div id="selector" class="navbar navbar-default"> <ul class="nav navbar-nav"> <li><a href="#one">one</a> </li> <li><a href="#two">two</a> </li> <li><a href="#three">three</a> </li> </ul></div><div data-spy="scroll" data-target="#selector" style="height:100px; overflow:hidden;overflow-y: auto;" > <h4 id="one" >ibe</h4><p>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/></p> <h4 id="two" >two</h4><p>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/></p> <h4 id="three" >three</h4><p>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/>One的具體內容<br/></p></div>
下面來看一下實現的具體代碼，原理：當滾動容器內的hashkey位置距離容器頂部只有 offset設置的值，就會設置導航中對應的href高亮。
ScrollSpy構造函數
首先新建一個構造函數，如下：
function ScrollSpy(element, options) { this.$body = $(document.body) this.$scrollElement = $(element).is(document.body) ? $(window) : $(element) this.options = $.extend({}, ScrollSpy.DEFAULTS, options) this.selector = (this.options.target || '') + ' .nav li > a' this.offsets = [] this.targets = [] this.activeTarget = null this.scrollHeight = 0 this.$scrollElement.on('scroll.bs.scrollspy', $.proxy(this.process, this)) this.refresh() this.process() }該構造函數主要干了啥：
1.基本設置，主要是設置當前滾動元素是設置的body還是具體的某一塊元素；其次是導航的結構要是.nav li > a的結構，也就是你的菜單中也要有.nav這個class。
2.監聽元素滾動的時候，執行process方法。
3.同時初始化的時候也執行了refresh與process方法。
下面講解一下這幾個方法。
getScrolHeight方法
獲取滾動容器的內容高度（包含被隱藏部分）
this.$scrollElement[0].scrollHeight || Math.max(this.$body[0].scrollHeight, document.documentElement.scrollHeight)
refresh方法
刷新并存儲滾動容器內各hashkey的值
ScrollSpy.prototype.refresh = function () { var that = this var offsetMethod = 'offset' var offsetBase = 0 this.offsets = [] this.targets = [] this.scrollHeight = this.getScrollHeight() if (!$.isWindow(this.$scrollElement[0])) { offsetMethod = 'position' offsetBase = this.$scrollElement.scrollTop() } this.$body .find(this.selector) .map(function () { var $el = $(this) var href = $el.data('target') || $el.attr('href') var $href = /^#./.test(href) && $(href) return ($href && $href.length && $href.is(':visible') && [[$href[offsetMethod]().top + offsetBase, href]]) || null }) .sort(function (a, b) { return a[0] - b[0] }) .each(function () { that.offsets.push(this[0]) that.targets.push(this[1]) }) }它主要實現了什么呢？
1.默認用offset來獲取定位值，如果滾動區域不是window則用position來獲取
if (!$.isWindow(this.$scrollElement[0])) { offsetMethod = 'position' offsetBase = this.$scrollElement.scrollTop() }2.根據導航上的hashkey來遍歷獲取 滾動區域內的hashkey對應的offset值：
this.$body .find(this.selector) .map(function () { var $el = $(this) var href = $el.data('target') || $el.attr('href') var $href = /^#./.test(href) && $(href) return ($href && $href.length && $href.is(':visible') && [[$href[offsetMethod]().top + offsetBase, href]]) || null }) .sort(function (a, b) { return a[0] - b[0] }) .each(function () { that.offsets.push(this[0]) that.targets.push(this[1]) })process方法
滾動條事件觸發函數，用于計算當前需要高亮那個導航菜單
ScrollSpy.prototype.process = function () { var scrollTop = this.$scrollElement.scrollTop() + this.options.offset var scrollHeight = this.getScrollHeight() var maxScroll = this.options.offset + scrollHeight - this.$scrollElement.height() var offsets = this.offsets var targets = this.targets var activeTarget = this.activeTarget var i if (this.scrollHeight != scrollHeight) { this.refresh() } if (scrollTop >= maxScroll) { return activeTarget != (i = targets[targets.length - 1]) && this.activate(i) } if (activeTarget && scrollTop < offsets[0]) { this.activeTarget = null return this.clear() } for (i = offsets.length; i--;) { activeTarget != targets[i] && scrollTop >= offsets[i] && (offsets[i + 1] === undefined || scrollTop < offsets[i + 1]) && this.activate(targets[i]) } }主要作用：
1.獲取滾動容器已滾動距離：
var scrollTop = this.$scrollElement.scrollTop() + this.options.offset
2.滾動容器可以滾動的最大高度:
var maxScroll = this.options.offset + scrollHeight - this.$scrollElement.height()
3.設置滾動元素邏輯，給當前匹配元素添加高亮：
for (i = offsets.length; i--;) { activeTarget != targets[i] && scrollTop >= offsets[i] && (offsets[i + 1] === undefined || scrollTop < offsets[i + 1]) && this.activate(targets[i]) }active方法
設置指定的導航菜單高亮
ScrollSpy.prototype.activate = function (target) { this.activeTarget = target this.clear() var selector = this.selector + '[data-target="' + target + '"],' + this.selector + '[href="' + target + '" rel="external nofollow" rel="external nofollow" ]' var active = $(selector) .parents('li') .addClass('active') if (active.parent('.dropdown-menu').length) { active = active .closest('li.dropdown') .addClass('active') } active.trigger('activate.bs.scrollspy') }clear方法
清除所有高亮菜單
ScrollSpy.prototype.clear = function () { $(this.selector) .parentsUntil(this.options.target, '.active') .removeClass('active') } 源碼
+function ($) { 'use strict'; // SCROLLSPY CLASS DEFINITION // ========================== function ScrollSpy(element, options) { this.$body = $(document.body) this.$scrollElement = $(element).is(document.body) ? $(window) : $(element) this.options = $.extend({}, ScrollSpy.DEFAULTS, options) this.selector = (this.options.target || '') + ' .nav li > a' this.offsets = [] this.targets = [] this.activeTarget = null this.scrollHeight = 0 this.$scrollElement.on('scroll.bs.scrollspy', $.proxy(this.process, this)) this.refresh() this.process() } ScrollSpy.VERSION = '3.3.7' ScrollSpy.DEFAULTS = { offset: 10 } ScrollSpy.prototype.getScrollHeight = function () { return this.$scrollElement[0].scrollHeight || Math.max(this.$body[0].scrollHeight, document.documentElement.scrollHeight) } ScrollSpy.prototype.refresh = function () { var that = this var offsetMethod = 'offset' var offsetBase = 0 this.offsets = [] this.targets = [] this.scrollHeight = this.getScrollHeight() if (!$.isWindow(this.$scrollElement[0])) { offsetMethod = 'position' offsetBase = this.$scrollElement.scrollTop() } this.$body .find(this.selector) .map(function () { var $el = $(this) var href = $el.data('target') || $el.attr('href') var $href = /^#./.test(href) && $(href) return ($href && $href.length && $href.is(':visible') && [[$href[offsetMethod]().top + offsetBase, href]]) || null }) .sort(function (a, b) { return a[0] - b[0] }) .each(function () { that.offsets.push(this[0]) that.targets.push(this[1]) }) } ScrollSpy.prototype.process = function () { var scrollTop = this.$scrollElement.scrollTop() + this.options.offset var scrollHeight = this.getScrollHeight() var maxScroll = this.options.offset + scrollHeight - this.$scrollElement.height() var offsets = this.offsets var targets = this.targets var activeTarget = this.activeTarget var i if (this.scrollHeight != scrollHeight) { this.refresh() } if (scrollTop >= maxScroll) { return activeTarget != (i = targets[targets.length - 1]) && this.activate(i) } if (activeTarget && scrollTop < offsets[0]) { this.activeTarget = null return this.clear() } for (i = offsets.length; i--;) { activeTarget != targets[i] && scrollTop >= offsets[i] && (offsets[i + 1] === undefined || scrollTop < offsets[i + 1]) && this.activate(targets[i]) } } ScrollSpy.prototype.activate = function (target) { this.activeTarget = target this.clear() var selector = this.selector + '[data-target="' + target + '"],' + this.selector + '[href="' + target + '" rel="external nofollow" rel="external nofollow" ]' var active = $(selector) .parents('li') .addClass('active') if (active.parent('.dropdown-menu').length) { active = active .closest('li.dropdown') .addClass('active') } active.trigger('activate.bs.scrollspy') } ScrollSpy.prototype.clear = function () { $(this.selector) .parentsUntil(this.options.target, '.active') .removeClass('active') } // SCROLLSPY PLUGIN DEFINITION // =========================== function Plugin(option) { return this.each(function () { var $this = $(this) var data = $this.data('bs.scrollspy') var options = typeof option == 'object' && option if (!data) $this.data('bs.scrollspy', (data = new ScrollSpy(this, options))) if (typeof option == 'string') data[option]() }) } var old = $.fn.scrollspy $.fn.scrollspy = Plugin $.fn.scrollspy.Constructor = ScrollSpy // SCROLLSPY NO CONFLICT // ===================== $.fn.scrollspy.noConflict = function () { $.fn.scrollspy = old return this } // SCROLLSPY DATA-API // ================== $(window).on('load.bs.scrollspy.data-api', function () { $('[data-spy="scroll"]').each(function () { var $spy = $(this) Plugin.call($spy, $spy.data()) }) })}(jQuery);以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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