无法从数组中获取相关值，出现 Uncaught TypeError "Cannot use 'in' operator to search 'length"

Posted 2023-05-09

【中文标题】无法从数组中获取相关值，出现 Uncaught TypeError "Cannot use \'in\' operator to search \'length"

【英文标题】：Not able to get the relevant value from array, getting Uncaught TypeError "Cannot use 'in' operator to search for 'length"无法从数组中获取相关值，出现 Uncaught TypeError "Cannot use 'in' operator to search 'length"

【发布时间】：2021-10-06 03:48:45

【问题描述】：

我需要从数组中获取所选选项的相关值。

我的选择：

<select id="BestMobileSelect">
    <option></option>
    <option value=Mobile-SmartPhone-Motorola>Motorola</option>
    <option value=Mobile-SmartPhone-Samsung>Samsung</option>
    <option value=Mobile-SmartPhone-Xiaomi>Xiaomi</option>
</select>

数组：

var BestMobileJSON = 
    "Mobile-SmartPhone-Motorola" : ["Price":"Rs.12000"],
    "Mobile-SmartPhone-Samsung" : ["Price":"Rs.15000"],
    "Mobile-SmartPhone-Xiaomi" : ["Price":"Rs.9000"],

我用来获取相关值的jquery如下：

$("#BestMobileSelect").on("change", function () 
        var BestMobileSelected = $(this).val()

        var markup = '';
        jQuery.each(BestMobileSelected, function(index, value)
            markup += '<div>' + BestMobileJSON[value][0].Price +'</div>'
        );

    $("#BestMobileResult").html(markup);
    );

但是，这不起作用，我收到错误 Uncaught TypeError: Cannot use 'in' operator to search for 'length' in Mobile-SmartPhone-Motorola

为什么这不起作用？

在下面找到完整的代码：

jQuery(document).ready(function($) 
  var BestMobileJSON = 
    "Mobile-SmartPhone-Motorola": [
      "Price": "Rs.12000"
    ],
    "Mobile-SmartPhone-Samsung": [
      "Price": "Rs.15000"
    ],
    "Mobile-SmartPhone-Xiaomi": [
      "Price": "Rs.9000"
    ],
  

  $("#BestMobileSelect").on("change", function() 
    var BestMobileSelected = $(this).val()

    var markup = '';
    jQuery.each(BestMobileSelected, function(index, value) 
      markup += '<div>' + BestMobileJSON[value][0].Price + '</div>'
    );

    $("#BestMobileResult").html(markup);
  );

);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>

<select id="BestMobileSelect">
  <option></option>
  <option value=Mobile-SmartPhone-Motorola>Motorola</option>
  <option value=Mobile-SmartPhone-Samsung>Samsung</option>
  <option value=Mobile-SmartPhone-Xiaomi>Xiaomi</option>
</select>

<div id="BestMobileResult"></div>

【问题讨论】：

$.each() 的第一个参数必须是数组或对象。 BestMobileSelected 是一个字符串。

【参考方案1】：

$.each() 的参数必须是数组或对象，但 BestMobileSelected 是字符串。您应该使用下拉值作为BestMobileJSON 对象的索引；这将返回一个数组，然后您可以使用 $.each() 循环遍历该数组。

jQuery(document).ready(function($) 
  var BestMobileJSON = 
    "Mobile-SmartPhone-Motorola": [
      "Price": "Rs.12000"
    ],
    "Mobile-SmartPhone-Samsung": [
      "Price": "Rs.15000"
    ],
    "Mobile-SmartPhone-Xiaomi": [
      "Price": "Rs.9000"
    ],
  

  $("#BestMobileSelect").on("change", function() 
    var markup = '';
    let val = $(this).val();
    if (val) 
      var BestMobileSelected = BestMobileJSON[val];
      jQuery.each(BestMobileSelected, function(index, value) 
        markup += '<div>' + value.Price + '</div>'
      );
    
    $("#BestMobileResult").html(markup);
  );
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>

<select id="BestMobileSelect">
  <option></option>
  <option value=Mobile-SmartPhone-Motorola>Motorola</option>
  <option value=Mobile-SmartPhone-Samsung>Samsung</option>
  <option value=Mobile-SmartPhone-Xiaomi>Xiaomi</option>
</select>

<div id="BestMobileResult"></div>