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mirror of https://github.com/twbs/bootstrap.git synced 2024-12-04 16:24:22 +01:00
Bootstrap/js/affix.js

165 lines
4.8 KiB
JavaScript

/* ========================================================================
* Bootstrap: affix.js v3.4.1
* https://getbootstrap.com/docs/3.4/javascript/#affix
* ========================================================================
* Copyright 2011-2019 Twitter, Inc.
* Licensed under MIT (https://github.com/twbs/bootstrap/blob/v3-dev/LICENSE)
* ======================================================================== */
+function ($) {
'use strict';
// AFFIX CLASS DEFINITION
// ======================
var Affix = function (element, options) {
this.options = $.extend({}, Affix.DEFAULTS, options)
var target = this.options.target === Affix.DEFAULTS.target ? $(this.options.target) : $(document).find(this.options.target)
this.$target = target
.on('scroll.bs.affix.data-api', $.proxy(this.checkPosition, this))
.on('click.bs.affix.data-api', $.proxy(this.checkPositionWithEventLoop, this))
this.$element = $(element)
this.affixed = null
this.unpin = null
this.pinnedOffset = null
this.checkPosition()
}
Affix.VERSION = '3.4.1'
Affix.RESET = 'affix affix-top affix-bottom'
Affix.DEFAULTS = {
offset: 0,
target: window
}
Affix.prototype.getState = function (scrollHeight, height, offsetTop, offsetBottom) {
var scrollTop = this.$target.scrollTop()
var position = this.$element.offset()
var targetHeight = this.$target.height()
if (offsetTop != null && this.affixed == 'top') return scrollTop < offsetTop ? 'top' : false
if (this.affixed == 'bottom') {
if (offsetTop != null) return (scrollTop + this.unpin <= position.top) ? false : 'bottom'
return (scrollTop + targetHeight <= scrollHeight - offsetBottom) ? false : 'bottom'
}
var initializing = this.affixed == null
var colliderTop = initializing ? scrollTop : position.top
var colliderHeight = initializing ? targetHeight : height
if (offsetTop != null && scrollTop <= offsetTop) return 'top'
if (offsetBottom != null && (colliderTop + colliderHeight >= scrollHeight - offsetBottom)) return 'bottom'
return false
}
Affix.prototype.getPinnedOffset = function () {
if (this.pinnedOffset) return this.pinnedOffset
this.$element.removeClass(Affix.RESET).addClass('affix')
var scrollTop = this.$target.scrollTop()
var position = this.$element.offset()
return (this.pinnedOffset = position.top - scrollTop)
}
Affix.prototype.checkPositionWithEventLoop = function () {
setTimeout($.proxy(this.checkPosition, this), 1)
}
Affix.prototype.checkPosition = function () {
if (!this.$element.is(':visible')) return
var height = this.$element.height()
var offset = this.options.offset
var offsetTop = offset.top
var offsetBottom = offset.bottom
var scrollHeight = Math.max($(document).height(), $(document.body).height())
if (typeof offset != 'object') offsetBottom = offsetTop = offset
if (typeof offsetTop == 'function') offsetTop = offset.top(this.$element)
if (typeof offsetBottom == 'function') offsetBottom = offset.bottom(this.$element)
var affix = this.getState(scrollHeight, height, offsetTop, offsetBottom)
if (this.affixed != affix) {
if (this.unpin != null) this.$element.css('top', '')
var affixType = 'affix' + (affix ? '-' + affix : '')
var e = $.Event(affixType + '.bs.affix')
this.$element.trigger(e)
if (e.isDefaultPrevented()) return
this.affixed = affix
this.unpin = affix == 'bottom' ? this.getPinnedOffset() : null
this.$element
.removeClass(Affix.RESET)
.addClass(affixType)
.trigger(affixType.replace('affix', 'affixed') + '.bs.affix')
}
if (affix == 'bottom') {
this.$element.offset({
top: scrollHeight - height - offsetBottom
})
}
}
// AFFIX PLUGIN DEFINITION
// =======================
function Plugin(option) {
return this.each(function () {
var $this = $(this)
var data = $this.data('bs.affix')
var options = typeof option == 'object' && option
if (!data) $this.data('bs.affix', (data = new Affix(this, options)))
if (typeof option == 'string') data[option]()
})
}
var old = $.fn.affix
$.fn.affix = Plugin
$.fn.affix.Constructor = Affix
// AFFIX NO CONFLICT
// =================
$.fn.affix.noConflict = function () {
$.fn.affix = old
return this
}
// AFFIX DATA-API
// ==============
$(window).on('load', function () {
$('[data-spy="affix"]').each(function () {
var $spy = $(this)
var data = $spy.data()
data.offset = data.offset || {}
if (data.offsetBottom != null) data.offset.bottom = data.offsetBottom
if (data.offsetTop != null) data.offset.top = data.offsetTop
Plugin.call($spy, data)
})
})
}(jQuery);