• jQuery1


    什么是jQuery

    jQuery内部封装了原生的js代码(还额外添加了很多的功能)
    能够让你通过书写更少的代码 完成js操作
    类似于python里面的模块  在前端模块不叫模块  “类库”

    jQuery的优点

    兼容多个浏览器的 你在使用jQuery的时候就不需要考虑浏览器兼容问题
    更少的代码完成更多的事情

    学习步骤

    选择器
    筛选器
    样式操作
    文本操作
    属性操作
    文档处理
    事件
    动画效果
    插件
    each、data、Ajax(重点 django部分学)

    jQuery的导入问题

    • 文件下载到本地的导入方式

    可以借助于pycharm自动初始化代码功能完成自动添加
    配置
      编辑
         file and code template
    • 直接引入jQuery的CDN服务(基于网络直接请求加载)

    CDN:内容分发网络
       免费的CDN网站:bootcdn
            <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
      """你的计算机必须要有网络"""

    jQuery的基本语法

    jQuery(选择器).action()
      秉持着jQuery的宗旨 jQuery简写 $
      jQuery() === $()
    ps:相对js的代码jQuery的代码非常精简
    // 原生js代码操作标签
    let pEle = document.getElementById('d1')
    pEle.style.color = 'red'

    // jQuery操作标签
    $('p').css('color','blue')

    jQuery查找标签

    • 基本选择器

    // id选择器
    $('#d1')
    w.fn.init [div#d1]0: div#d1length: 1__proto__: Object(0)
    // class选择器
    $('.c1')
    w.fn.init [p.c1, prevObject: w.fn.init(1)]0: p.c1length: 1prevObject: w.fn.init [document]__proto__: Object(0)
    // 标签选择器
    $('span')
    w.fn.init(3) [span, span, span, prevObject: w.fn.init(1)]

    """一定要区分开(重点)"""
    // jQuery对象如何变成标签对象
    undefined
    $('#d1')[0]
    <div id="d1"></div>
    document.getElementById('d1')
    <div id="d1"></div>
    // 标签对象如何转jQuery对象
    undefined
    $(document.getElementById('d1'))
    w.fn.init [div#d1]

    组合选择器/分组和嵌套

    $('div')
    w.fn.init(2) [div#d1, div.c1, prevObject: w.fn.init(1)]
    $('div.c1')
    w.fn.init [div.c1, prevObject: w.fn.init(1)]0: div.c1length: 1prevObject: w.fn.init [document]__proto__: Object(0)
    $('div#d1')
    w.fn.init [div#d1, prevObject: w.fn.init(1)]
    $('*')
    w.fn.init(19) [html, head, meta, title, meta, link, script, script, body, span, span, div#d1, span, p#d2, span, span, div.c1, span, span, prevObject: w.fn.init(1)]
                  
    $('#d1,.c1,p'# 并列+混用
    w.fn.init(3) [div#d1, p#d2, div.c1, prevObject: w.fn.init(1)]
                 
    $('div span'# 后代
    w.fn.init(3) [span, span, span, prevObject: w.fn.init(1)]
    $('div>span'# 儿子
    w.fn.init(2) [span, span, prevObject: w.fn.init(1)]
    $('div+span'# 毗邻
    w.fn.init [span, prevObject: w.fn.init(1)]
    $('div~span'# 弟弟
    w.fn.init(2) [span, span, prevObject: w.fn.init(1)]

    基本筛选器

    $('ul li')
    w.fn.init(10) [li, li, li, li, li, li, li.c1, li, li#d1, li, prevObject: w.fn.init(1)]
                  
    $('ul li:first'# 大儿子
    w.fn.init [li, prevObject: w.fn.init(1)]0: lilength: 1prevObject: w.fn.init [document]__proto__: Object(0)
                  
    $('ul li:last'# 小儿子
    w.fn.init [li, prevObject: w.fn.init(1)]0: lilength: 1prevObject: w.fn.init [document]__proto__: Object(0)
                  
    $('ul li:eq(2)') # 放索引
    w.fn.init [li, prevObject: w.fn.init(1)]0: lilength: 1prevObject: w.fn.init [document]__proto__: Object(0)
                  
    $('ul li:even'# 偶数索引 0包含在内
    w.fn.init(5) [li, li, li, li.c1, li#d1, prevObject: w.fn.init(1)]0: li1: li2: li3: li.c14: li#d1length: 5prevObject: w.fn.init [document]__proto__: Object(0)
                 
    $('ul li:odd'# 奇数索引
    w.fn.init(5) [li, li, li, li, li, prevObject: w.fn.init(1)]0: li1: li2: li3: li4: lilength: 5prevObject: w.fn.init [document]__proto__: Object(0)
                 
    $('ul li:gt(2)'# 大于索引
    w.fn.init(7) [li, li, li, li.c1, li, li#d1, li, prevObject: w.fn.init(1)]0: li1: li2: li3: li.c14: li5: li#d16: lilength: 7prevObject: w.fn.init [document]__proto__: Object(0)
                 
    $('ul li:lt(2)'# 小于索引
    w.fn.init(2) [li, li, prevObject: w.fn.init(1)]0: li1: lilength: 2prevObject: w.fn.init [document]__proto__: Object(0)
                 
    $('ul li:not("#d1")'# 移除满足条件的标签
    w.fn.init(9) [li, li, li, li, li, li, li.c1, li, li, prevObject: w.fn.init(1)]
            
    $('div')
    w.fn.init(2) [div, div, prevObject: w.fn.init(1)]
    $('div:has("p")'# 选取出包含一个或多个标签在内的标签
    w.fn.init [div, prevObject: w.fn.init(1)]

    属性选择器

    $('[username]')
    w.fn.init(3) [input, input, p, prevObject: w.fn.init(1)]
    $('[username="jason"]')
    w.fn.init [input, prevObject: w.fn.init(1)]
    $('p[username="egon"]')
    w.fn.init [p, prevObject: w.fn.init(1)]

    $('[type]')
    w.fn.init(2) [input, input, prevObject: w.fn.init(1)]
    $('[type="text"]')
    w.fn.init(2) [input, input, prevObject: w.fn.init(1)]

    表单筛选器

    $('input[type="text"]')
    w.fn.init [input, prevObject: w.fn.init(1)]0: inputlength: 1prevObject: w.fn.init [document]__proto__: Object(0)
    $('input[type="password"]')
    w.fn.init [input, prevObject: w.fn.init(1)]

    $(':text'# 等价于上面第一个
    w.fn.init [input, prevObject: w.fn.init(1)]0: inputlength: 1prevObject: w.fn.init [document]__proto__: Object(0)
    $(':password'# 等价于上面第二个
    w.fn.init [input, prevObject: w.fn.init(1)]


    :text
    :password
    :file
    :radio
    :checkbox
    :submit
    :reset
    :button
    ...

    表单对象属性
    :enabled
    :disabled
    :checked
    :selected
    """特殊情况"""
    $(':checked'# 它会将checked和selected都拿到
    w.fn.init(2) [input, option, prevObject: w.fn.init(1)]0: input1: optionlength: 2prevObject: w.fn.init [document]__proto__: Object(0)
    $(':selected'# 它不会 只拿selected
    w.fn.init [option, prevObject: w.fn.init(1)]
    $('input:checked'# 自己加一个限制条件
    w.fn.init [input, prevObject: w.fn.init(1)]

    筛选器方法

    $('#d1').next()  # 同级别下一个
    w.fn.init [span, prevObject: w.fn.init(1)]0: spanlength: 1prevObject: w.fn.init [span#d1]__proto__: Object(0)
    $('#d1').nextAll()
    w.fn.init(5) [span, div#d2, span, span, span.c1, prevObject: w.fn.init(1)]0: span1: div#d22: span3: span4: span.c1length: 5prevObject: w.fn.init [span#d1]__proto__: Object(0)
    $('#d1').nextUntil('.c1'# 不包括最后一个
    w.fn.init(4) [span, div#d2, span, span, prevObject: w.fn.init(1)]0: span1: div#d22: span3: spanlength: 4prevObject: w.fn.init [span#d1]__proto__: Object(0)
                 
                 
    $('.c1').prev()  # 上一个
    w.fn.init [span, prevObject: w.fn.init(1)]0: spanlength: 1prevObject: w.fn.init [span.c1, prevObject: w.fn.init(1)]__proto__: Object(0)
    $('.c1').prevAll()
    w.fn.init(5) [span, span, div#d2, span, span#d1, prevObject: w.fn.init(1)]
    $('.c1').prevUntil('#d2')
    w.fn.init(2) [span, span, prevObject: w.fn.init(1)]
                 
    $('#d3').parent()  # 第一级父标签
    w.fn.init [p, prevObject: w.fn.init(1)]0: plength: 1prevObject: w.fn.init [span#d3]__proto__: Object(0)
    $('#d3').parent().parent()
    w.fn.init [div#d2, prevObject: w.fn.init(1)]
    $('#d3').parent().parent().parent()
    w.fn.init [body, prevObject: w.fn.init(1)]
    $('#d3').parent().parent().parent().parent()
    w.fn.init [html, prevObject: w.fn.init(1)]
    $('#d3').parent().parent().parent().parent().parent()
    w.fn.init [document, prevObject: w.fn.init(1)]
    $('#d3').parent().parent().parent().parent().parent().parent()
    w.fn.init [prevObject: w.fn.init(1)]
    $('#d3').parents()
    w.fn.init(4) [p, div#d2, body, html, prevObject: w.fn.init(1)]
    $('#d3').parentsUntil('body')
    w.fn.init(2) [p, div#d2, prevObject: w.fn.init(1)]
                 
                 
    $('#d2').children()  # 儿子
                
    $('#d2').siblings()  # 同级别上下所有
                
                 
                 
    $('div p')
    # 等价          
    $('div').find('p'# find从某个区域内筛选出想要的标签
                
                 
    """下述两两等价"""
    $('div span:first')
    w.fn.init [span, prevObject: w.fn.init(1)]
    $('div span').first()
    w.fn.init [span, prevObject: w.fn.init(3)]0: spanlength: 1prevObject: w.fn.init(3) [span, span#d3, span, prevObject: w.fn.init(1)]__proto__: Object(0)
                                                                                       
    $('div span:last')
    w.fn.init [span, prevObject: w.fn.init(1)]
    $('div span').last()
                                                                                       
    w.fn.init [span, prevObject: w.fn.init(3)]
    $('div span:not("#d3")')
    w.fn.init(2) [span, span, prevObject: w.fn.init(1)]
    $('div span').not('#d3')
    w.fn.init(2) [span, span, prevObject: w.fn.init(3)]

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  • 原文地址:https://www.cnblogs.com/bailongcaptain/p/12919096.html
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