我双手接过晶莹的雪花，想数一数它有几朵花瓣，谁知它到手上就不见了，变成了小水珠。
Tooltip插件可以让你把要显示的内容以弹出框的形式来展示，如：
因为自己在工作的过程中，用到了Tooltip这个插件，并且当时正想学习一下元素定位的问题，如：提示框显示的位置就是触发提示框元素的位置，可以配置在上、下、左、右等位置，所以就去看了源码。对于整个插件源码没有看全，但也学到了许多的知识点。能力有限，可能其中有认识错误的地方，以后再补充吧
1 使用方法不介绍 ，可以参照
Bootstrap 提示工具（Tooltip）插件
2 源码解析
+function ($) {
'use strict';
// TOOLTIP PUBLIC CLASS DEFINITION
// ===============================
var Tooltip = function (element, options) {
this.type =
this.options =
this.enabled =
this.timeout =
this.hoverState =
this.$element = null
this.init('tooltip', element, options)
}
Tooltip.VERSION = '3.3.0'
Tooltip.TRANSITION_DURATION = 150
//默认参数
Tooltip.DEFAULTS = {
animation: true,
placement: 'top',
selector: false,
template: '<div class="tooltip" role="tooltip"><div class="tooltip-arrow"></div><div class="tooltip-inner"></div></div>',
trigger: 'hover focus',
title: '',
delay: 0,
html: false,
container: false,
viewport: {
selector: 'body',
padding: 0
}
}
//初始化
Tooltip.prototype.init = function (type, element, options) {
this.enabled = true
this.type = type
this.$element = $(element)
//初始化参数
this.options = this.getOptions(options)
this.$viewport = this.options.viewport && $(this.options.viewport.selector || this.options.viewport)
//多个触发器 即触发函数
var triggers = this.options.trigger.split(' ')
for (var i = triggers.length; i--;) {
var trigger = triggers[i]
if (trigger == 'click') {
//绑定事件处理程序
//事件命名空间 'click.tooltip'
//触发时执行$.proxy(this.toggle, this)返回的函数
this.$element.on('click.' + this.type, this.options.selector, $.proxy(this.toggle, this))
} else if (trigger != 'manual') {
var eventIn = trigger == 'hover' ? 'mouseenter' : 'focusin'
var eventOut = trigger == 'hover' ? 'mouseleave' : 'focusout'
this.$element.on(eventIn + '.' + this.type, this.options.selector, $.proxy(this.enter, this))
this.$element.on(eventOut + '.' + this.type, this.options.selector, $.proxy(this.leave, this))
}
}
this.options.selector ?
(this._options = $.extend({}, this.options, { trigger: 'manual', selector: '' })) :
this.fixTitle()
}
Tooltip.prototype.getDefaults = function () {
return Tooltip.DEFAULTS
}
//获得初始化参数
Tooltip.prototype.getOptions = function (options) {
// this.$element.data() data-key = value 形式的属性获取
// 返回一个对象{key:value}
// options > 元素属性 > 默认
options = $.extend({}, this.getDefaults(), this.$element.data(), options)
//delay 为数字 特殊处理
//delay 为对象 delay:{ show: 500, hide: 100 }
if (options.delay && typeof options.delay == 'number') {
options.delay = {
show: options.delay,
hide: options.delay
}
}
return options
}
Tooltip.prototype.getDelegateOptions = function () {
var options = {}
var defaults = this.getDefaults()
this._options && $.each(this._options, function (key, value) {
if (defaults[key] != value) options[key] = value
})
return options
}
//提示框显示
Tooltip.prototype.enter = function (obj) {
//obj是否是tooltip的实例
var self = obj instanceof this.constructor ?
obj : $(obj.currentTarget).data('bs.' + this.type)
//$tip.is(':visible') 该div是否可见
//可见时 只更新状态 然后直接返回
if (self && self.$tip && self.$tip.is(':visible')) {
self.hoverState = 'in'
return
}
//self 不存在
if (!self) {
self = new this.constructor(obj.currentTarget, this.getDelegateOptions())
$(obj.currentTarget).data('bs.' + this.type, self)
}
//上次点击延时未显示 则取消显示
clearTimeout(self.timeout)
//设置状态
self.hoverState = 'in'
//delay: 数字 (默认 0) 或 对象 { show: 500, hide: 100 }
//没有delay delay.show 时 直接显示
if (!self.options.delay || !self.options.delay.show) return self.show()
//延时显示 self.options.delay.show:延时时间
self.timeout = setTimeout(function () {
if (self.hoverState == 'in') self.show()
}, self.options.delay.show)
}
//提示框隐藏
Tooltip.prototype.leave = function (obj) {
var self = obj instanceof this.constructor ?
obj : $(obj.currentTarget).data('bs.' + this.type)
if (!self) {
self = new this.constructor(obj.currentTarget, this.getDelegateOptions())
$(obj.currentTarget).data('bs.' + this.type, self)
}
clearTimeout(self.timeout)
self.hoverState = 'out'
if (!self.options.delay || !self.options.delay.hide) return self.hide()
self.timeout = setTimeout(function () {
if (self.hoverState == 'out') self.hide()
}, self.options.delay.hide)
}
//提示框显示核心方法
Tooltip.prototype.show = function () {
console.info(this)
var e = $.Event('show.bs.' + this.type)
if (this.hasContent() && this.enabled) {
this.$element.trigger(e)
//判断是否在根节点中
//this.$element[0] 转换为DOM对象
//.ownerDocument Document文档对象
//.documentElement 根节点 HTML标签
//$.contains 一个DOM节点是否包含另一个DOM节点。
var inDom = $.contains(this.$element[0].ownerDocument.documentElement, this.$element[0])
//调用preventDefault 或 不在根节点 return
//事件对象中是否调用过 event.preventDefault()
//event.preventDefault():阻止元素发生默认的行为
//如 当点击提交按钮时阻止对表单的提交 、 阻止以下 URL 的链接
if (e.isDefaultPrevented() || !inDom) return
var that = this
var $tip = this.tip()
var tipId = this.getUID(this.type)
//设置提示框的title
this.setContent()
$tip.attr('id', tipId)
this.$element.attr('aria-describedby', tipId)
//参数animation
if (this.options.animation) $tip.addClass('fade')
//参数placement 提示框的位置 top bottom left right
var placement = typeof this.options.placement == 'function' ?
this.options.placement.call(this, $tip[0], this.$element[0]) :
this.options.placement
// 判断placement是否包含"auto"
var autoToken = /\s?auto?\s?/i
var autoPlace = autoToken.test(placement)
//包含 "auto"时
if (autoPlace) placement = placement.replace(autoToken, '') || 'top'
$tip
//detach() 删除匹配的对象 与remove()不同的是，所有绑定的事件、附加的数据等都会保留下来
.detach()
.css({ top: 0, left: 0, display: 'block' })
.addClass(placement)
.data('bs.' + this.type, this)
//参数 container 向指定元素添加该提示框
//没有 添加到当前元素后面
this.options.container ? $tip.appendTo(this.options.container) : $tip.insertAfter(this.$element)
//位置对象pos pos = {top: , right: , bottom: , left: , width: ,scroll:}
var pos = this.getPosition()
//提示框自身实际的 width height
var actualWidth = $tip[0].offsetWidth
var actualHeight = $tip[0].offsetHeight
if (autoPlace) {
var orgPlacement = placement
var $container = this.options.container ? $(this.options.container) : this.$element.parent()
var containerDim = this.getPosition($container)
placement = placement == 'bottom' && pos.bottom + actualHeight > containerDim.bottom ? 'top' :
placement == 'top' && pos.top - actualHeight < containerDim.top ? 'bottom' :
placement == 'right' && pos.right + actualWidth > containerDim.width ? 'left' :
placement == 'left' && pos.left - actualWidth < containerDim.left ? 'right' :
placement
$tip
.removeClass(orgPlacement)
.addClass(placement)
}
//计算提示框的偏移量 {top: , left: }
var calculatedOffset = this.getCalculatedOffset(placement, pos, actualWidth, actualHeight)
//应用并设置偏移量
this.applyPlacement(calculatedOffset, placement)
var complete = function () {
var prevHoverState = that.hoverState
that.$element.trigger('shown.bs.' + that.type)
that.hoverState = null
if (prevHoverState == 'out') that.leave(that)
}
$.support.transition && this.$tip.hasClass('fade') ?
$tip
.one('bsTransitionEnd', complete)
.emulateTransitionEnd(Tooltip.TRANSITION_DURATION) :
complete()
}
}
Tooltip.prototype.applyPlacement = function (offset, placement) {
var $tip = this.tip()
var width = $tip[0].offsetWidth
var height = $tip[0].offsetHeight
// manually read margins because getBoundingClientRect includes difference
//获得提示框自身的外边距的值
var marginTop = parseInt($tip.css('margin-top'), 10)
var marginLeft = parseInt($tip.css('margin-left'), 10)
// we must check for NaN for ie 8/9
//是否是非数字
if (isNaN(marginTop)) marginTop = 0
if (isNaN(marginLeft)) marginLeft = 0
//计算的偏移量 + 自身的外边距
offset.top = offset.top + marginTop
offset.left = offset.left + marginLeft
// $.fn.offset doesn't round pixel values
// so we use setOffset directly with our own function B-0
// 应用了offset.setOffset方法，传入了using参数，因为offset设置值的时候，不能四舍五入
$.offset.setOffset($tip[0], $.extend({
using: function (props) {
$tip.css({
top: Math.round(props.top),
left: Math.round(props.left)
})
}
}, offset), 0)
//添加 in class 让提示框显示
$tip.addClass('in')
// check to see if placing tip in new offset caused the tip to resize itself
//获取显示后的提示框的宽和高 检查是否调整了自身的大小
var actualWidth = $tip[0].offsetWidth
var actualHeight = $tip[0].offsetHeight
if (placement == 'top' && actualHeight != height) {
offset.top = offset.top + height - actualHeight
}
var delta = this.getViewportAdjustedDelta(placement, offset, actualWidth, actualHeight)
if (delta.left) offset.left += delta.left
else offset.top += delta.top
var isVertical = /top|bottom/.test(placement)
var arrowDelta = isVertical ? delta.left * 2 - width + actualWidth : delta.top * 2 - height + actualHeight
var arrowOffsetPosition = isVertical ? 'offsetWidth' : 'offsetHeight'
$tip.offset(offset)
this.replaceArrow(arrowDelta, $tip[0][arrowOffsetPosition], isVertical)
}
Tooltip.prototype.replaceArrow = function (delta, dimension, isHorizontal) {
this.arrow()
.css(isHorizontal ? 'left' : 'top', 50 * (1 - delta / dimension) + '%')
.css(isHorizontal ? 'top' : 'left', '')
}
//设置提示框的title
Tooltip.prototype.setContent = function () {
//div
var $tip = this.tip()
var title = this.getTitle()
$tip.find('.tooltip-inner')[this.options.html ? 'html' : 'text'](title)
$tip.removeClass('fade in top bottom left right')
}
Tooltip.prototype.hide = function (callback) {
var that = this
var $tip = this.tip()
var e = $.Event('hide.bs.' + this.type)
function complete() {
if (that.hoverState != 'in') $tip.detach()
that.$element
.removeAttr('aria-describedby')
.trigger('hidden.bs.' + that.type)
callback && callback()
}
this.$element.trigger(e)
if (e.isDefaultPrevented()) return
$tip.removeClass('in')
$.support.transition && this.$tip.hasClass('fade') ?
$tip
.one('bsTransitionEnd', complete)
.emulateTransitionEnd(Tooltip.TRANSITION_DURATION) :
complete()
this.hoverState = null
return this
}
Tooltip.prototype.fixTitle = function () {
var $e = this.$element
if ($e.attr('title') || typeof ($e.attr('data-original-title')) != 'string') {
$e.attr('data-original-title', $e.attr('title') || '').attr('title', '')
}
}
Tooltip.prototype.hasContent = function () {
return this.getTitle()
}
//获取位置
Tooltip.prototype.getPosition = function ($element) {
//不传入 则为当前点击元素
$element = $element || this.$element
//转换为DOM对象
var el = $element[0]
//是否是body元素
var isBody = el.tagName == 'BODY'
//获取元素各边与页面上边和左边的距离 left right top bottom height width
var elRect = el.getBoundingClientRect()
//兼容IE8 没有 width height 则计算
if (elRect.width == null) {
// width and height are missing in IE8, so compute them manually; see https://github.com/twbs/bootstrap/issues/14093
elRect = $.extend({}, elRect, { width: elRect.right - elRect.left, height: elRect.bottom - elRect.top })
}
//当前元素相对于文档的偏移量
var elOffset = isBody ? { top: 0, left: 0 } : $element.offset()
//垂直滚动条的距离
//document.documentElement.scrollTop 和 document.body.scrollTop 浏览器兼容
var scroll = { scroll: isBody ? document.documentElement.scrollTop || document.body.scrollTop : $element.scrollTop() }
var outerDims = isBody ? { width: $(window).width(), height: $(window).height() } : null
//合并
return $.extend({}, elRect, scroll, outerDims, elOffset)
}
//计算偏移量
Tooltip.prototype.getCalculatedOffset = function (placement, pos, actualWidth, actualHeight) {
return placement == 'bottom' ? { top: pos.top + pos.height, left: pos.left + pos.width / 2 - actualWidth / 2 } :
placement == 'top' ? { top: pos.top - actualHeight, left: pos.left + pos.width / 2 - actualWidth / 2 } :
placement == 'left' ? { top: pos.top + pos.height / 2 - actualHeight / 2, left: pos.left - actualWidth } :
/* placement == 'right' */ { top: pos.top + pos.height / 2 - actualHeight / 2, left: pos.left + pos.width }
}
Tooltip.prototype.getViewportAdjustedDelta = function (placement, pos, actualWidth, actualHeight) {
var delta = { top: 0, left: 0 }
//默认参数
//viewport: {
// selector: 'body',
// padding: 0
//}
//默认的话 this.$viewport = 'body'
if (!this.$viewport) return delta
var viewportPadding = this.options.viewport && this.options.viewport.padding || 0
//this.$viewport = 'body' width height为 window的
var viewportDimensions = this.getPosition(this.$viewport)
console.info(viewportDimensions)
if (/right|left/.test(placement)) {
var topEdgeOffset = pos.top - viewportPadding - viewportDimensions.scroll
var bottomEdgeOffset = pos.top + viewportPadding - viewportDimensions.scroll + actualHeight
if (topEdgeOffset < viewportDimensions.top) { // top overflow
delta.top = viewportDimensions.top - topEdgeOffset
} else if (bottomEdgeOffset > viewportDimensions.top + viewportDimensions.height) { // bottom overflow
delta.top = viewportDimensions.top + viewportDimensions.height - bottomEdgeOffset
}
} else {
var leftEdgeOffset = pos.left - viewportPadding
var rightEdgeOffset = pos.left + viewportPadding + actualWidth
if (leftEdgeOffset < viewportDimensions.left) { // left overflow
delta.left = viewportDimensions.left - leftEdgeOffset
} else if (rightEdgeOffset > viewportDimensions.width) { // right overflow
delta.left = viewportDimensions.left + viewportDimensions.width - rightEdgeOffset
}
}
return delta
}
//提示框的title
Tooltip.prototype.getTitle = function () {
var title
var $e = this.$element
var o = this.options
//先获取当前元素的data-original-title属性
//否则获取参数title
title = $e.attr('data-original-title')
|| (typeof o.title == 'function' ? o.title.call($e[0]) : o.title)
return title
}
//随机生成唯一id 0 -- 100000 id值
Tooltip.prototype.getUID = function (prefix) {
//~~ 去掉小数部分
do prefix += ~~(Math.random() * 1000000)
while (document.getElementById(prefix))
return prefix
}
//生成提示框的div
//不存在 则用模板
//<div class="tooltip" role="tooltip"><div class="tooltip-arrow"></div><div class="tooltip-inner"></div></div>
Tooltip.prototype.tip = function () {
return (this.$tip = this.$tip || $(this.options.template))
}
Tooltip.prototype.arrow = function () {
return (this.$arrow = this.$arrow || this.tip().find('.tooltip-arrow'))
}
Tooltip.prototype.enable = function () {
this.enabled = true
}
Tooltip.prototype.disable = function () {
this.enabled = false
}
Tooltip.prototype.toggleEnabled = function () {
this.enabled = !this.enabled
}
//click 事件触发时执行的函数
Tooltip.prototype.toggle = function (e) {
//this tooltip实例对象
var self = this
if (e) {
//e.currentTarget 返回注册该事件处理程序的元素
self = $(e.currentTarget).data('bs.' + this.type)
if (!self) {
self = new this.constructor(e.currentTarget, this.getDelegateOptions())
$(e.currentTarget).data('bs.' + this.type, self)
}
}
//判断提示框当前的状态
//true 当前显示 需要隐藏
//false 相反
self.tip().hasClass('in') ? self.leave(self) : self.enter(self)
}
Tooltip.prototype.destroy = function () {
var that = this
clearTimeout(this.timeout)
this.hide(function () {
that.$element.off('.' + that.type).removeData('bs.' + that.type)
})
}
// TOOLTIP PLUGIN DEFINITION
// =========================
function Plugin(option) {
return this.each(function () {
var $this = $(this)
//所选元素是否有 key为:bs.tooltip 对应的value值
var data = $this.data('bs.tooltip')
//option为对象 options:option
//option为字符串 则是方法 options:false
var options = typeof option == 'object' && option
//option是对象 执行初始化 ，并提供了选择器
var selector = options && options.selector
//是destroy 方法 不执行
if (!data && option == 'destroy') return
//tooltip初始化
if (selector) {
//存在选择器，则将当前点击元素 bs.tooltip = {} 即去掉Tooltip实例
if (!data) $this.data('bs.tooltip', (data = {}))
//给选择器加上Tooltip实例
if (!data[selector]) data[selector] = new Tooltip(this, options)
} else {
//没有value值时，则加上 bs.tooltip = data(new Tooltip(this, options))
if (!data) $this.data('bs.tooltip', (data = new Tooltip(this, options)))
}
//执行方法
if (typeof option == 'string') data[option]()
})
}
//缓存以前$.fn上的tooltip
var old = $.fn.tooltip
//添加到jQuery对象上
$.fn.tooltip = Plugin
$.fn.tooltip.Constructor = Tooltip
// TOOLTIP NO CONFLICT
// ===================
//tooltip冲突时 调用该方法
//var other = $("#aa").tooltip().noConflict();
$.fn.tooltip.noConflict = function () {
$.fn.tooltip = old
return this
}
}(jQuery);
本文BootStrap Tooltip插件源码解析到此结束。在这个忧伤而明媚的三月，我从我单薄的青春里打马而过，穿过紫堇，穿过木棉，穿过时隐时现的悲喜和无常。小编再次感谢大家对我们的支持！