如何通過選定的選項設置彈出菜單中的更改？

Question

我有以下選擇：

<form> 
<select id="poSelect" > 
<option selected disabled>Choose here</option> 
<option id="buyeroption" value="100101">I am a Buyer</option>                   
<option id="garageoption" value="100102">I am a Garage</option>                   
</select> 

<label>Full Name</label> 
<input type="text" /> 

<label>Email Address</label> 
<input type="email" /> 

<label>Password</label> 
<input type="password" /> 

<label id="industrylabel" >Select Your Brand</label> 
<select id="industryoption"> 
<option selected disabled>Select</option> 
<option value="Renault">Renault</option> 
<option value="Pegaut">Pegaut</option> 
<option value="Citroen">Citroen</option> 
</select> 

<div class="form-check-label"> 
<input id="send_updates" type="checkbox" /> 
<label for="send_updates">Send me occasional email updates</label> 
</div> 

所以我需要的是，當用戶選擇我是一個買方標籤「選擇你的品牌」和產業選項選擇要隱藏，但是當我點擊我的車庫出現。

Answer 1

<form> 
<select id="mySelect"> 
<option id="apple">Apple</option> 
<option id="orange">Orange</option> 
<option id="pineapple">Pineapple</option> 
<option id="banana">Banana</option> 
</select> 
</form> 
<p></p> 

<button onclick="myFunction()">textbox1</button> 
<p id="demo"></p> 
<script> 
function myFunction() { 
var x = document.getElementById("mySelect").options.namedItem("banana").text; 
document.getElementById("demo").innerHTML = x; 
} 
</script> 

也許你想這樣的事情，如果你想改變任何事情，請檢查此鏈接： - http://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_select_options6