jQuery 简介

• 线上练习环境 http://jsbin.com/ 或 https://jsfiddle.net/
• jQuery
  • 官网文件 http://api.jquery.com/
  • 版本1.x 2.x 的差异
  • 用途
    • 定位 selectors & Traverse
    • 修改 DOM manipulation
    • 绑事件 Event
    • 动画 animate
    • API 串接 Ajax
• Selector
  • by tag
  • by class
  • by id
  • by attribute https://api.jquery.com/category/selectors/attribute-selectors/
  • Filter https://api.jquery.com/category/selectors/basic-filter-selectors/
• Traverse 常用于从 $(this) 出发去找目标
  • parents
  • parent
  • closest
  • first
  • last
  • prev
  • next
  • find 找下多层
  • children 只找下一层而已
  • filter
• DOM manipulation
  • 插入
    • append
    • prepend
    • after
    • before
    • appendTo
    • prependTo
    • insertAfter
    • insertBefore
  • remove
  • attr
    • 例如超连结的 attr(“href”)
  • text
  • html
  • val
    • 针对 input, select and textarea 的 value 资料
  • css
  • toggleClass
    • addClass
    • removeClass
  • toggle
    • show
    • hide
  • slideToggle
    • slideDown
    • slideUp
  • fadeToggle
    • fadeIn
    • fadeOut
  • animate
• Event
  • ready
  • on
    • Direct event v.s. Delegated event
    • http://jsbin.com/tinopojeni/1/edit?html,js,output
  • click
  • trigger 指定事件
  • Mouse events: click, focusin, mousedown, mousemove, mouseover, mouseenter, dbclock, focusout, mouseup
  • Keyboard Events: keypress, keydown, keyup
  • Form events: blur, select, change, focus, submit
  • bubble up 特性
  • 如何阻止超连结 # 作用? event.preventDefault()
  • 停止往上传递事件 event.stopPropagation()

参考资料

• Udacity: JavaScript Basic
• Udacity: Intro to jQuery
• CodeSchool: Try jQuery

Example Code:

• https://github.com/ihower/rails-exercise-ac5/blob/master/app/views/welcome/jquery.html.erb (ac5)
• https://github.com/ihower/rails-exercise-ac6/blob/master/app/views/welcome/jquery.html.erb (ac6)
• https://github.com/ihower/rails-exercise-ac7/blob/master/app/views/welcome/jquery.html.erb (ac7)

Ajax

• Ajax = JavaScript 送 Request，然后处理 response，过程中浏览器不会跳一整页。
• facebook and twitter timeline example: it’s JSON including HTML
• append 第三方图片，用 img src (但这不算是 ajax)
• Debugging with Chrome DevTools

jQuery 的 Ajax 用法

官方文件 >http://api.jquery.com/category/ajax/>

• jQuery $.ajax

       $.ajax( <url>, { success: function(res) {  $(<selector>).html(res) } } )
       $.get(<url>, function(res) { ... })
       $.ajax( <url>, { data: { foobar: 1 },  success: function(res) {  $(<selector>).html(res) } } )
* Ajax Error handling (e.g. timeout)
       $ajax(<url>, { success: function(res){ ... }, error: function(request, error_type, error_message) { ... } } )
       $ajax(<url>, { success: function(res){ ... }, error: function(request, error_type, error_message) { ... } , timeout: 3000 } )

• Add ajax loading status?
  • beforeSend
  • complete
• 小心动态插入的 element 会没有绑到 event。要使用 Delegated Event
• Ajax Form

       $('form').on("submit", function(e) { 
          e.preventDefault();
          $.ajax( <url>, { type: 'POST', data: { "foo":  $("#foo").val() }    }); 

• 其中 data: $('form').serialize()
  • https://api.jquery.com/serialize/
• 注意: 无法处理档案上传
• 再补上 success callback 把 form 移掉等等
• JSON Response
  • $.ajax 加上
    • dataType: ‘json’ 代表 parse the response as JSON
    • contentType: ‘application/json’ 跟 server 说要 JSON 格式
    • success callback 的 response 变成 json object 了
    • codeschool 这里手动组 HTML
    • ajax url 可以换成 $('form').attr('action')
  • $.getJSON(url, function(data){ … } )
  • $.getJSON(url, function(data){ … } ).error(function(e){…} )

关于 jQuery Ajax，推荐以下两个教材：

• Udacity: Intro to Ajax
• codeSchool: jQuery The Return Flight