jQuery .each() 索引？

Question

我用来

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

循环列表中的选项。 我想知道如何获取当前循环的索引？

因为我不想让 var i = 0; 循环内有 i++;

Answer 1

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

记录索引:)

下面是更详细的示例。

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 会为您处理这个问题。 .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 元素所以：

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

Answer 3

从 jQuery.each() 文档：

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

所以你会想要使用：

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

...where index将是索引，元素将是列表中的选项元素

Answer 4

惊讶地发现没有人给出这个语法。

带有数据或集合的 .each 语法

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

OR

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

Answer 5

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