Detailed explanation of jquery selector practice

This article will bring you a basic selector practice of jquery (explanation with examples). The editor thinks it’s pretty good, so I’ll share it with you now and give it as a reference. Let’s follow the editor to take a look, I hope it can help everyone.

1. Enter the number in the input box and click the button to implement the function of the corresponding event.

html code:

<input id="txt1" type="text" value="2" />
<input id="Button5" type="button" value="改变大于N的行背景为绿色" />

jQuery code:

//改变大于N的行背景为绿色
      $("#Button5").click(function () {
　　　　　　　　//获取到ID为txt1的输入框的文本值
        var num = $("#txt1").val();
　　　　　　　　//tr的行的下标从0开始，故现实中的数字应该减一
        num = num - 1;
        $("tr:gt("+num+")").css("background-color", "green");
      });

2. When you click on the p in each blue wireframe, change the background of the element immediately behind it to green

html code:

<p class="mainbox">
    <p>1</p>
    <p>2</p>
    <p>3</p>
    <p>4</p>
    <p>5</p>
    <p>6</p>
    <p>7</p>
    <p>8</p>
    <p>9</p>
  </p>

jQuery code:

 $("p").click(function () {
         $(this).next("p").css("background-color","green");
       });

After the page is loaded, change the font color of all p's with odd numbers to blue

//2.页面加载完毕后，让所有数字为奇数的p的字体颜色该为blue
      //$("p.mainbox>p:even").css("color", "blue");
      for (var i = 0; i < $(".mainbox>p").length; i++) {
        //获取到每p的集合
        var valu = $(".mainbox>p");
        //获取到每一个p中的文本内容
        var txt = $(valu[i]).text();
        //将string转换为int
        value = parseInt(txt);
        //取模进行奇偶判断
        if (value%2!=0) {
          $(valu[i]).css("color", "blue");
        }
      }

3. Write javascript code to complete the following functional requirements:

Realize all selection, inverse selection, and none selection functions

HTML code:

<tr>
        <td>
          <label>
            <input type="radio" name="selectMode" id="selectAll" />全选
          </label>
          <label>
            <input type="radio" name="selectMode" id="selectNotAll" />全不选
          </label>
          <label>
            <input type="radio" name="selectMode" id="selectRevorse" />反选
          </label>
        </td>
      </tr>
      <tr>
        <td>
          <label>
            <input type="checkbox" id="Checkbox3" />刘德华
          </label>
          <label>
            <input type="checkbox" id="Checkbox4" />张学友
          </label>
          <label>
            <input type="checkbox" id="Checkbox5" />孙燕姿
          </label>
          <label>
            <input type="checkbox" id="Checkbox6" />刘欢
          </label>
        </td>
      </tr>

jQuery code:

$(function () {
      //全选
      //方法1：
      $("#selectAll").click(function () {
        $("#Checkbox3,#Checkbox4,#Checkbox5,#Checkbox6").prop("checked",true);
      });
      //方法2：
      $("#selectAll").click(function () {
        //:checkbox--选取所有类型为checkbox的input标签
        $(":checkbox").prop("checked", true);
      });
      //全不选
      $("#selectNotAll").click(function () {
        $(":checkbox").prop("checked", false);
      });
      //反选方法1：
      $("#selectRevorse").click(function () {
        $(":checkbox").each(function () {
          $(this).prop("checked", !$(this).prop("checked"));
        });
      });
      //反选方法二2：
      $("#selectRevorse").click(function () {
        $("input[type=checked]").each(function (i, n) {
          n.checked = !n.checked;
        });
      });
      //反选方法3：
      $("#selectRevorse").click(function () {
        var $bob = $("input[type=checked]");
        for (var i = 0; i < $bob.length; i++) {
          if ($bob[i].checked == true) {
            $bob[i].checked == false;
          }
          else {
            $bob[i].checked == true;
          }
        }
      });
    });

4. Change the foreground color of all son p tags under p tags to red

Change the foreground color of all grandchild span tags under p tags to green

Change the foreground color of i’s grandfather to Orange

HTML code:

<p>
    <span>七大洲有哪些：大米粥、小米粥、绿豆粥、八宝粥... ...</span>
    <p>
      <span>中国四大发明时什么：油盐酱醋</span>
    </p>
    <p>
      我拿什么拯救你，<span>我的<i>瞌睡虫</i></span>

    </p>
  </p>

jQuery code:

$(function () {
      //将所有p标记下的儿子p前景色改为red
      $("#Button1").click(function () {
        $("p>p").css("color","red");
      });
      //将所有p标记的孙子span前景色改为green
      $("#Button2").click(function () {
        $("p").children().children().css("color","green");
      });
      //将i的的爷爷的前景色改为Orange
      $("#Button3").click(function () {
        $("i").parent().parent().css("color","orange");
      });
    });

5. Please write javascript code and complete as follows Functional requirements:

Every 1 second, rotate all numbers counterclockwise

The effect is as follows:

HTML code :

<p class="box">
    <table id="table1" class="mytable">
      <tr>
        <td>
          <label id="Label1">
            1
          </label>
        </td>
        <td>
          <label id="Label2">
            2
          </label>
        </td>

jQuery code:

$(function () {
      window.setInterval(fun, 1000);
    });
    //方法一：
    function fun() {
      $("#table1 label").each(function (i, n) {
        //获取到当前label的文本值
        var $item = $(n).text();
        //将其转换为int型
        $item = parseInt($item);        
        if ($item == 8) {
          //给当前label赋值
          $(n).text("1");
        }
        else {
          //给当前label赋值
          $(n).text($item+1);
        }
      });
    };
    //方法二：
    function fun2() {
      $("#table1 label").each(function () {
        var n = $(this).text();
        n++;
        if (n > 8) {
          n = 1;
        }
        this.textContent = n;
        //$(this).text() = n;
      });
    }

Related recommendations:

Detailed explanation of CSS attribute selector

Detailed explanation of the use of hover selector in CSS

jQuery selector symbol analysis

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