jQuery .each（）索引？

Question

我正在使用

$('#list option').each(function(){
//do stuff
});

循环遍历列表中的选项。 我想知道如何获得当前循环的索引？

因为我不想让var i = 0; 并且在循环内部有i ++;

Answer 1

$('#list option').each(function(index){
  //do stuff
  console.log(index);
});

记录索引：）

下面是一个更详细的例子。

function run_each() {

  var $results = $(".results");

  $results.empty();

  $results.append("==================== START 1st each ====================");
  console.log("==================== START 1st each ====================");

  $('#my_select option').each(function(index, value) {
    $results.append("<br>");
    // log the index
    $results.append("index: " + index);
    $results.append("<br>");
    console.log("index: " + index);
    // logs the element
    // $results.append(value);  this would actually remove the element
    $results.append("<br>");
    console.log(value);
    // logs element property
    $results.append(value.innerHTML);
    $results.append("<br>");
    console.log(value.innerHTML);
    // logs element property
    $results.append(this.text);
    $results.append("<br>");
    console.log(this.text);
    // jquery
    $results.append($(this).text());
    $results.append("<br>");
    console.log($(this).text());

    // BEGIN just to see what would happen if nesting an .each within an .each
    $('p').each(function(index) {
      $results.append("==================== nested each");
      $results.append("<br>");
      $results.append("nested each index: " + index);
      $results.append("<br>");
      console.log(index);
    });
    // END just to see what would happen if nesting an .each within an .each

  });

  $results.append("<br>");
  $results.append("==================== START 2nd each ====================");
  console.log("");
  console.log("==================== START 2nd each ====================");


  $('ul li').each(function(index, value) {
    $results.append("<br>");
    // log the index
    $results.append("index: " + index);
    $results.append("<br>");
    console.log(index);
    // logs the element
    // $results.append(value); this would actually remove the element
    $results.append("<br>");
    console.log(value);
    // logs element property
    $results.append(value.innerHTML);
    $results.append("<br>");
    console.log(value.innerHTML);
    // logs element property
    $results.append(this.innerHTML);
    $results.append("<br>");
    console.log(this.innerHTML);
    // jquery
    $results.append($(this).text());
    $results.append("<br>");
    console.log($(this).text());
  });

}



$(document).on("click", ".clicker", function() {

  run_each();

});

.results {
  background: #000;
  height: 150px;
  overflow: auto;
  color: lime;
  font-family: arial;
  padding: 20px;
}

.container {
  display: flex;
}

.one,
.two,
.three {
  width: 33.3%;
}

.one {
  background: yellow;
  text-align: center;
}

.two {
  background: pink;
}

.three {
  background: darkgray;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div class="container">

  <div class="one">
    <select id="my_select">
      <option>apple</option>
      <option>orange</option>
      <option>pear</option>
    </select>
  </div>

  <div class="two">
    <ul id="my_list">
      <li>canada</li>
      <li>america</li>
      <li>france</li>
    </ul>
  </div>

  <div class="three">
    <p>do</p>
    <p>re</p>
    <p>me</p>
  </div>

</div>

<button class="clicker">run_each()</button>


<div class="results">


</div>

Answer 2

jQuery为您解决此问题。 .each()回调函数的第一个参数是循环当前迭代的索引。第二个是当前匹配的DOM元素So：

$('#list option').each(function(index, element){
  alert("Iteration: " + index)
});

Answer 3

来自jQuery.each() documentation：

.each( function(index, Element) )
    function(index, Element)A function to execute for each matched element.

所以你想要使用：

$('#list option').each(function(i,e){
    //do stuff
});

...其中index将是索引，而element将是list

中的option元素

Answer 4

$('#list option').each(function(intIndex){
//do stuff
});

Answer 5

惊讶地发现没有给出这种语法。

带有数据或集合的

jQuery.each(collection, callback(indexInArray, valueOfElement)); 语法

jQuery.each( jQuery('#list option'), function(indexInArray, valueOfElement){
//your code here
}); 

OR

public class UserPrivacyData {

    private static String password = null;
    private final static String USER = "root";
    final String DRIVER = "org.apache.derby.jdbc.EmbeddedDriver";
    final String DATABASE_URL = "jdbc:derby://localhost:1527/USERPRIVACYDB;create=true;";

    public void loadDB() throws SQLException {
        try {
            Class.forName(DRIVER); //load the driver
              connection = DriverManager.getConnection(DATABASE_URL, USER, password);
      statement = connection.createStatement();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
String sql = "insert into USERPRIVACYDB values('" + gender[rand.nextInt(2)] + "',"
                    + " '" + privacyLevel[rand.nextInt(3)] + "', '" + age[rand.nextInt(3)] + "',"
                    + " '" + presentEducationLevel[rand.nextInt(3)] + "',"
                    + " '" + highestEducation[rand.nextInt(3)] + "', '"
                    + everVictimOfCrimeString + "', "
                    + " '" + crimeTypeString + "', "
                    + " '" + shareWithThirdParty[rand.nextInt(2)] + "',"
                    + " '" + reasonforChoiceofPrivacy[rand.nextInt(5)] + "')";

            statement.executeUpdate(sql);
           // }

        }

    }