JavaScript与选项交互 [英] JavaScript Interacting with options

问题描述

我目前有一个下拉列表...来完成空白句子。

我遇到的问题是Uncaught TypeError：无法读取null的属性'options'

这里是一个片段我的HTML

 < section class =question-three> 
< h4>问题3< / h4> 
< ol> 
< li>合作关系是商业实体
< select id =selectionOne> 
< option value =＃>请选择...< / option> 
< option value =唯一交易者>独家交易者< / option> 
< option value =members>成员< / option> 
< option value =股东>股东< / option> 
< option value =run>运行< / option> 
< option value =有限公司>有限公司< / option> 
< option value =拥有>拥有< / option> 
< / select> 
由两个或两个以上的人共同进行业务以谋取利润。 
< / li> 
  

JavaScript

  var dropDownList = {
答案：['单独交易者'，'成员'，'股东'，'跑'，'有限公司'，'拥有']，
 checkAnswer：function ）{
 var check = document.getElementById（'selectionOne'）; 
 
 if（check.options == dropDownList.answers [5]）{
 console.log（'The answer is right！'）; 
} else {
 console.log（'false'）
} 
} 
}; 
 
 dropDownList.checkAnswer（）; 
  

任何人都可以帮我吗？

谢谢

解决方案

您没有访问值。我们也不知道您何时触发该事件。您需要在select已经呈现后分配它：

var dropDownList = {answers：['single trader'，'members'，'stakeholder '，'run'，'limited company'，'owned']，checkAnswer：function（）{var check = document.getElementById（'selectionOne'）; if（check.value == dropDownList.answers [5]）{console.log（'The answer is right！'）; } else {console.log（'false'）}}}; window.onload = function（）{document.getElementById（checkIt）。onclick = function（）{dropDownList.checkAnswer（）; } // // document.getElementById（selectionOne）。onchange}

 < section class =问题三> < h4>问题3< / h4> <醇> < li>伙伴关系是商业实体< select id =selectionOne> < option value =＃>请选择...< / option> < option value =唯一交易者>独家交易者< / option> < option value =members>成员< / option> < option value =股东>股东< / option> < option value =run>运行< / option> < option value =有限公司>有限公司< / option> < option value =拥有>拥有< / option> < /选择>由两个或更多的人进行集体合作以谋取利润。 < / li>< button id =checkIt>检查< / button>  

I currently have a dropdown list... to finish blank sentences off.

The problem I have is Uncaught TypeError: Cannot read property 'options' of null

Here is a snippet of my HTML

<section class="question-three">
                <h4>Question 3</h4>
                <ol>
                    <li>A partnership is a business entity 
                    <select id="selectionOne">
                        <option value="#">Please Select...</option>
                        <option value="sole trader">sole trader</option>
                        <option value="members">members</option>
                        <option value="shareholders">shareholders</option>
                        <option value="run">run</option>
                        <option value="limited company">limited company</option>
                        <option value="owned">owned</option>
                    </select>
                    by two ore more people who carry a business collectively with a view to making a profit.
                </li>

JavaScript

var dropDownList = {
    answers: ['sole trader', 'members', 'shareholders', 'run', 'limited company', 'owned'],
    checkAnswer: function() {
        var check = document.getElementById('selectionOne');

        if(check.options == dropDownList.answers[5]) {
            console.log('The answer is right!');
        } else {
            console.log('false')
        }
    }
};

dropDownList.checkAnswer();

Could anyone please help me?

Thank You

解决方案

You are not accessing the value. We also do not know when you trigger the event. You need to assign it after the select has rendered:

var dropDownList = {
    answers: ['sole trader', 'members', 'shareholders', 'run', 'limited company', 'owned'],
    checkAnswer: function() {
        var check = document.getElementById('selectionOne');

        if(check.value == dropDownList.answers[5]) {
            console.log('The answer is right!');
        } else {
            console.log('false')
        }
    }
};
window.onload=function() {
  document.getElementById("checkIt").onclick=function() {
    dropDownList.checkAnswer();
  }
  // or document.getElementById("selectionOne").onchange
}

<section class="question-three">
                <h4>Question 3</h4>
                <ol>
                    <li>A partnership is a business entity 
                    <select id="selectionOne">
                        <option value="#">Please Select...</option>
                        <option value="sole trader">sole trader</option>
                        <option value="members">members</option>
                        <option value="shareholders">shareholders</option>
                        <option value="run">run</option>
                        <option value="limited company">limited company</option>
                        <option value="owned">owned</option>
                    </select>
                    by two ore more people who carry a business collectively with a view to making a profit.
                </li>
<button id="checkIt">Check</button>

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