Bootstrap滚动监听组件scrollspy.js使用方法详解

Bootstrap滚动监听组件scrollspy.js使用方法详解

其实滚动监听使用的情况还是很多的，比如导航居于右侧，当主题内容滚动某一块的时候，右侧导航对应的要高亮。

实现功能

1、当滚动区域内设置的hashkey距离顶点到有效位置时，就关联设置其导航上的指定项
2、导航必须是 .nav > li > a 结构，并且a上href或data-target要绑定hashkey
3、菜单上必须有.nav样式
4、滚动区域的data-target与导航父级Id（一定是父级）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的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/></p> <h4 id="two" >two</h4><p>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/></p> <h4 id="three" >three</h4><p>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/>One的具体内容<br/></p></div>

下面来看一下实现的具体代码，原理：当滚动容器内的hashkey位置距离容器顶部只有 offset设置的值，就会设置导航中对应的href高亮。

ScrollSpy构造函数

首先新建一个构造函数，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() }

该构造函数主要干了啥：

1.基本设置，主要是设置当前滚动元素是设置的body还是具体的某一块元素；其次是导航的结构要是.nav li > a的结构，也就是你的菜单中也要有.nav这个class。

2.监听元素滚动的时候，执行process方法。

3.同时初始化的时候也执行了refresh与process方法。

下面讲解一下这几个方法。

getScrolHeight方法

获取滚动容器的内容高度（包含被隐藏部分）

this.$scrollElement[0].scrollHeight || Math.max(this.$body[0].scrollHeight, document.documentElement.scrollHeight)

refresh方法

刷新并存储滚动容器内各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])   }) }

它主要实现了什么呢？

1.默认用offset来获取定位值，如果滚动区域不是window则用position来获取

if (!$.isWindow(this.$scrollElement[0])) {   offsetMethod = 'position'   offsetBase  = this.$scrollElement.scrollTop()  }

2.根据导航上的hashkey来遍历获取 滚动区域内的hashkey对应的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

滚动条事件触发函数，用于计算当前需要高亮那个导航菜单

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.获取滚动容器已滚动距离：

var scrollTop  = this.$scrollElement.scrollTop() + this.options.offset

2.滚动容器可以滚动的最大高度:

var maxScroll  = this.options.offset + scrollHeight - this.$scrollElement.height()

3.设置滚动元素逻辑，给当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

设置指定的导航菜单高亮

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

清除所有高亮菜单

ScrollSpy.prototype.clear = function () {  $(this.selector)   .parentsUntil(this.options.target, '.active')   .removeClass('active') }

 源码

+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内容，希望对大家的学习有所帮助，也希望大家多多支持。

tag：组件使用方法详解电脑软件Bootstrap

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