bootstrap-modal.js学习笔记(源码注释)

不念不忘少年蓝@ 2021-06-26 16:06 402阅读 0赞

主要知识点：

*  通过`on,one`注册自定义事件，并且只能通过`trigger`来触发
 *  计算滚动条的宽度，通过生成一个`div`节点，`overflow`为`scroll`，那么就有滚动条了，然后就可以计算出滚动条的宽度
 *  把变量绑定在该`dom`元素的`data`的某个属性上，这个很妙

/* ======================================================================== * Bootstrap: modal.js v3.3.7 * http://getbootstrap.com/javascript/#modals * ======================================================================== * Copyright 2011-2016 Twitter, Inc. * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE) * ======================================================================== */
    
    
    +function ($) { 
      'use strict';
    
      // MODAL CLASS DEFINITION
      // ======================
    
      var Modal = function (element, options) { 
        this.options             = options
        this.$body               = $(document.body)
        this.$element            = $(element)
        this.$dialog             = this.$element.find('.modal-dialog')
        this.$backdrop           = null
        this.isShown             = null
        this.originalBodyPad     = null
        this.scrollbarWidth      = 0
        this.ignoreBackdropClick = false
    
        if (this.options.remote) { 
          this.$element
            .find('.modal-content')
            .load(this.options.remote, $.proxy(function () { 
              this.$element.trigger('loaded.bs.modal')
            }, this))
        }
      }
    
      Modal.VERSION  = '3.3.7'
    
      Modal.TRANSITION_DURATION = 300
      Modal.BACKDROP_TRANSITION_DURATION = 150
    
      Modal.DEFAULTS = { 
        backdrop: true,
        keyboard: true,
        show: true
      }
    
      Modal.prototype.toggle = function (_relatedTarget) { 
        return this.isShown ? this.hide() : this.show(_relatedTarget)
      }
    
      // 第一个被调用的函数
      Modal.prototype.show = function (_relatedTarget) { 
        // _relatedTarget是触发的按钮或a
    
        // this指向modal实例
    
        var that = this
    
        // relatedTarget是jq event的属性,返回当前事件涉及到的其他dom元素,它的值是一个dom节点
        var e    = $.Event('show.bs.modal', {  relatedTarget: _relatedTarget })
    
        // 执行了e事件
        this.$element.trigger(e)
    
        // 如果isShown为true那么下面的不执行,最初的isShow为null，因此那后isShown为false,所以就是如果没有modal显示，那么执行下面的代码
        if (this.isShown || e.isDefaultPrevented()) return
    
        this.isShown = true
    
        //检查浏览器滚动条的宽度
        this.checkScrollbar()
    
        // 如果溢出，给body的padding-right加上滚动条的宽度
        this.setScrollbar()
    
        // 'modal-open'的效果是overflow：hidden
        this.$body.addClass('modal-open')
    
        this.escape()
        this.resize()
    
        // 自定义事件click.dismiss.bs.modal
        this.$element.on('click.dismiss.bs.modal', '[data-dismiss="modal"]', $.proxy(this.hide, this))
    
        this.$dialog.on('mousedown.dismiss.bs.modal', function () { 
          that.$element.one('mouseup.dismiss.bs.modal', function (e) { 
            if ($(e.target).is(that.$element)) that.ignoreBackdropClick = true
          })
        })
    
        this.backdrop(function () { 
          var transition = $.support.transition && that.$element.hasClass('fade')
    
          if (!that.$element.parent().length) { 
            that.$element.appendTo(that.$body) // don't move modals dom position
          }
    
          that.$element
            .show()
            .scrollTop(0)
    
          that.adjustDialog()
    
          if (transition) { 
            that.$element[0].offsetWidth // force reflow
          }
    
          that.$element.addClass('in')
    
          that.enforceFocus()
    
          var e = $.Event('shown.bs.modal', {  relatedTarget: _relatedTarget })
    
          transition ?
            that.$dialog // wait for modal to slide in
              .one('bsTransitionEnd', function () { 
                that.$element.trigger('focus').trigger(e)
              })
              .emulateTransitionEnd(Modal.TRANSITION_DURATION) :
            that.$element.trigger('focus').trigger(e)
        })
      }
    
      Modal.prototype.hide = function (e) { 
        if (e) e.preventDefault()
    
        e = $.Event('hide.bs.modal')
    
        this.$element.trigger(e)
    
        if (!this.isShown || e.isDefaultPrevented()) return
    
        this.isShown = false
    
        this.escape()
        this.resize()
    
        $(document).off('focusin.bs.modal')
    
        this.$element
          .removeClass('in')
          .off('click.dismiss.bs.modal')
          .off('mouseup.dismiss.bs.modal')
    
        this.$dialog.off('mousedown.dismiss.bs.modal')
    
        $.support.transition && this.$element.hasClass('fade') ?
          this.$element
            .one('bsTransitionEnd', $.proxy(this.hideModal, this))
            .emulateTransitionEnd(Modal.TRANSITION_DURATION) :
          this.hideModal()
      }
    
      Modal.prototype.enforceFocus = function () { 
        $(document)
          .off('focusin.bs.modal') // guard against infinite focus loop
          .on('focusin.bs.modal', $.proxy(function (e) { 
            if (document !== e.target &&
                this.$element[0] !== e.target &&
                !this.$element.has(e.target).length) { 
              this.$element.trigger('focus')
            }
          }, this))
      }
    
      Modal.prototype.escape = function () { 
        console.log('this.isShown', this.isShown)
        console.log('this.options.keyboard', this.options.keyboard)
        if (this.isShown && this.options.keyboard) { 
          this.$element.on('keydown.dismiss.bs.modal', $.proxy(function (e) { 
            e.which == 27 && this.hide()
          }, this))
        } else if (!this.isShown) { 
          this.$element.off('keydown.dismiss.bs.modal')
        }
      }
    
      Modal.prototype.resize = function () { 
        if (this.isShown) { 
          $(window).on('resize.bs.modal', $.proxy(this.handleUpdate, this))
        } else { 
          $(window).off('resize.bs.modal')
        }
      }
    
      Modal.prototype.hideModal = function () { 
        var that = this
        this.$element.hide()
        this.backdrop(function () { 
          that.$body.removeClass('modal-open')
          that.resetAdjustments()
          that.resetScrollbar()
          that.$element.trigger('hidden.bs.modal')
        })
      }
    
      Modal.prototype.removeBackdrop = function () { 
        this.$backdrop && this.$backdrop.remove()
        this.$backdrop = null
      }
    
      Modal.prototype.backdrop = function (callback) { 
        var that = this
        var animate = this.$element.hasClass('fade') ? 'fade' : ''
    
        if (this.isShown && this.options.backdrop) { 
          var doAnimate = $.support.transition && animate
    
          this.$backdrop = $(document.createElement('div'))
            .addClass('modal-backdrop ' + animate)
            .appendTo(this.$body)
    
          this.$element.on('click.dismiss.bs.modal', $.proxy(function (e) { 
            if (this.ignoreBackdropClick) { 
              this.ignoreBackdropClick = false
              return
            }
            if (e.target !== e.currentTarget) return
            this.options.backdrop == 'static'
              ? this.$element[0].focus()
              : this.hide()
          }, this))
    
          if (doAnimate) this.$backdrop[0].offsetWidth // force reflow
    
          this.$backdrop.addClass('in')
    
          if (!callback) return
    
          doAnimate ?
            this.$backdrop
              .one('bsTransitionEnd', callback)
              .emulateTransitionEnd(Modal.BACKDROP_TRANSITION_DURATION) :
            callback()
    
        } else if (!this.isShown && this.$backdrop) { 
          this.$backdrop.removeClass('in')
    
          var callbackRemove = function () { 
            that.removeBackdrop()
            callback && callback()
          }
          $.support.transition && this.$element.hasClass('fade') ?
            this.$backdrop
              .one('bsTransitionEnd', callbackRemove)
              .emulateTransitionEnd(Modal.BACKDROP_TRANSITION_DURATION) :
            callbackRemove()
    
        } else if (callback) { 
          callback()
        }
      }
    
      // these following methods are used to handle overflowing modals
    
      Modal.prototype.handleUpdate = function () { 
        this.adjustDialog()
      }
    
      Modal.prototype.adjustDialog = function () { 
        var modalIsOverflowing = this.$element[0].scrollHeight > document.documentElement.clientHeight
    
        this.$element.css({ 
          paddingLeft:  !this.bodyIsOverflowing && modalIsOverflowing ? this.scrollbarWidth : '',
          paddingRight: this.bodyIsOverflowing && !modalIsOverflowing ? this.scrollbarWidth : ''
        })
      }
    
      Modal.prototype.resetAdjustments = function () { 
        this.$element.css({ 
          paddingLeft: '',
          paddingRight: ''
        })
      }
    
      Modal.prototype.checkScrollbar = function () { 
        //window.innerWidth,浏览器的视口宽度，包含滚动条的宽度
        var fullWindowWidth = window.innerWidth
        if (!fullWindowWidth) {  // workaround for missing window.innerWidth in IE8
          var documentElementRect = document.documentElement.getBoundingClientRect()
          fullWindowWidth = documentElementRect.right - Math.abs(documentElementRect.left)
        }
        // document.body.clientWidth是浏览器窗口的宽度，不包括滚动条
        this.bodyIsOverflowing = document.body.clientWidth < fullWindowWidth
        // 滚动条的宽度
        this.scrollbarWidth = this.measureScrollbar()
      }
    
      Modal.prototype.setScrollbar = function () { 
        var bodyPad = parseInt((this.$body.css('padding-right') || 0), 10)
        this.originalBodyPad = document.body.style.paddingRight || ''
        // 如果body，overflow，那么给body的padding-right加上滚动条的宽度
        if (this.bodyIsOverflowing) this.$body.css('padding-right', bodyPad + this.scrollbarWidth)
      }
    
      Modal.prototype.resetScrollbar = function () { 
        this.$body.css('padding-right', this.originalBodyPad)
      }
    
      Modal.prototype.measureScrollbar = function () {  // thx walsh
        var scrollDiv = document.createElement('div')
        scrollDiv.className = 'modal-scrollbar-measure'
        this.$body.append(scrollDiv)
        // offsetWidth,对象整体的实际宽度，包括滚动条等边线
        //clientWidth, 对象内容的宽度，不包括滚动条的宽度
        var scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth
        this.$body[0].removeChild(scrollDiv)
        return scrollbarWidth
      }
    
    
      // MODAL PLUGIN DEFINITION
      // =======================
    
      function Plugin(option, _relatedTarget) { 
        // _relatedTarget触发的按钮或者a标签
        // this是call函数指定的modal节点
    
        // 遍历页面中的所有modal节点
        return this.each(function () { 
          var $this   = $(this)
          var data    = $this.data('bs.modal')
          var options = $.extend({ }, Modal.DEFAULTS, $this.data(), typeof option == 'object' && option)
    
          // 如果data为空，那么给$(this).data('bs.modal')也就是data变量赋值,data变量现在是一个modal实例
          if (!data) { 
            $this.data('bs.modal',
              (data = new Modal(this, options))
            )
          }
    
          // 如果option是string
          if (typeof option == 'string') data[option](_relatedTarget)
    
          // 如果show为真，那么调用show函数
          else if (options.show) data.show(_relatedTarget)
        })
      }
    
      var old = $.fn.modal
    
      $.fn.modal             = Plugin
      $.fn.modal.Constructor = Modal
    
    
      // MODAL NO CONFLICT
      // =================
    
      $.fn.modal.noConflict = function () { 
        $.fn.modal = old
        return this
      }
    
    
      // MODAL DATA-API
      // ==============
    
      $(document).on('click.bs.modal.data-api', '[data-toggle="modal"]', function (e) { 
        var $this   = $(this)
        // 也就是触发modal的元素（button、a）
        var href    = $this.attr('href')
        var $target = $($this.attr('data-target') || (href && href.replace(/.*(?=#[^\s]+$)/, ''))) // strip for ie7
        // 找到页面中的modal节点
        var option  = $target.data('bs.modal') ? 'toggle' : $.extend({  remote: !/#/.test(href) && href }, $target.data(), $this.data())
    
        if ($this.is('a')) e.preventDefault()
    
        // 自定义事件'show.bs.modal',自定义事件只能通过on,one来‘绑定’
        $target.one('show.bs.modal', function (showEvent) { 
          if (showEvent.isDefaultPrevented()) return // only register focus restorer if modal will actually get shown
          $target.one('hidden.bs.modal', function () { 
            $this.is(':visible') && $this.trigger('focus')
          })
        })
    
        Plugin.call($target, option, this)
        // 这下Plugin里面的this指向的是$target
      })
    
    }(jQuery);