javascript - onchange =""在选择标签中不起作用

Question

我有两个选择标签。他们的ID是“study-phase”和“study-year”。我想在学习阶段处理一段CSS代码的值。

HTML:

<select name="study-phase" onchange="myFunction()" id="study-phase" class="sp-input">
    <option value=""></option>
    <option id="pri" value="pri">Primary</option>
    <option id="pre" value="pre">Prep</option>
    <option id="sec" value="sec">Secondary</option>
</select>   
<select name="study-year" id="study-year" class="sp-input">
    <option value=""></option>
    <option id="a" value="aa">Grade 1</option>
    <option id="b" value="">Grade 2</option>
    <option id="c" value="">Grade 3</option>
    <option id="d" value="">Grade 4</option>
    <option id="e" value="">Grade 5</option>
    <option id="f" value="">Grade 6</option>
    <option id="g" value="">Grade 7</option>
    <option id="h" value="">Grade 8</option>
    <option id="i" value="">Grade 9</option>
    <option id="j" value="">Grade 10</option>                       
</select>
<style type="text/css">
    #a , #b , #c , #d , #f , #g , #h , #j , #k , #e , #i {
        display: none;
    }
</style>

JS:

$(function(myFunction()){
   if (document.getElementById("study-phase").value == "pri") {
       document.getElementById("a").style.display = "block";
   }
});

在运行代码后，我想要的 css 代码不会启动。这里有什么问题？

Answer 1

$(function(myFunction()){
    if (document.getElementById("study-phase").value == "pri") {
        document.getElementById("a").style.display = "block";
    }});

报错

Uncaught SyntaxError: Unexpected token (

除了你修改你的代码如下它工作，因为它是 vanillaJs 你不需要 jquery

function myFunction() {
  if (document.getElementById("study-phase").value == "pri") {
    document.getElementById("a").style.display = "block";
  }
};

<select name="study-phase" onchange="myFunction()" id="study-phase" class="sp-input">
    <option value=""></option>
    <option id="pri" value="pri">Primary</option>
    <option id="pre" value="pre">Prep</option>
    <option id="sec" value="sec">Secondary</option>
</select>
<select name="study-year" id="study-year" class="sp-input">
    <option value=""></option>
    <option id="a" value="aa">Grade 1</option>
    <option id="b" value="">Grade 2</option>
    <option id="c" value="">Grade 3</option>
    <option id="d" value="">Grade 4</option>
    <option id="e" value="">Grade 5</option>
    <option id="f" value="">Grade 6</option>
    <option id="g" value="">Grade 7</option>
    <option id="h" value="">Grade 8</option>
    <option id="i" value="">Grade 9</option>
    <option id="j" value="">Grade 10</option>                       
</select>
<style type="text/css">
  #a,
  #b,
  #c,
  #d,
  #f,
  #g,
  #h,
  #j,
  #k,
  #e,
  #i {
    display: none;
  }
</style>