Javascript执行函数onload但不触发按钮的onclick事件[重复]

Question

您好，我刚刚学习了 javascript 查询事件处理函数，由于某种原因，即使我在结束 body 标记之前导入了 javascript，javascript 也会在加载时执行

由于某种原因，onclick 事件没有触发，请有人告诉我为什么！谢谢！

var starter=0;
var type;

var addstarter=document.querySelector("#addstarter");
addstarter.addEventListener("click",calculate("addstarter"));

var minusstarter=document.querySelector("#minusstarter");
minusstarter.addEventListener("click",calculate("minusstarter"));

function calculate(type)
{   
  switch(type)
  {
    case'addstarter': starter=starter+1;
    break;

    case 'minusstarter':starter=starter-1;
    break;
    }
    alert(starter);
}

#Starter
{
  float:left;
  width:25%;
  height:40%;
  background-color:rgb(55, 128, 85);
  color: white;
  margin: 5% 1% 1% 4%;
  padding: 1% 1% 1% 1%;
  color: black;
  border-radius: 10% 10% 10% 10%;
}

#Starter img
{
  width:50%;
  margin-top: -5%;
}

<main>
    <div id="Starter">
      
     <div class="card_border">
        <div class="card_heading">
         <p> Starter Pack </p>
        </div>
        <div class="card_content">
        <input type="button" value="+" class=" button button1" id="addstarter"/>
        <a href="https://en.wikipedia.org/wiki/Entr%C3%A9e"><img src="images/starterr.png"></a>
        <input type="button" value="-" class=" button button2" id="minusstarter"/>
        <span class="tooltiptext">$5</span>
        </div>
      </div>  
    </div>

Answer 1

你需要更换：

addstarter.addEventListener("click", calculate("addstarter"));

到：

addstarter.addEventListener("click", () => calculate("addstarter"));

Cause it should be a callback

var starter=0;
var type;

var addstarter=document.querySelector("#addstarter");
addstarter.addEventListener("click", () => calculate("addstarter"));

var minusstarter=document.querySelector("#minusstarter");
minusstarter.addEventListener("click", () => calculate("minusstarter"));

function calculate(type)
{   
  switch(type)
  {
    case'addstarter': starter=starter+1;
    break;

    case 'minusstarter':starter=starter-1;
    break;
    }
    alert(starter);
}

#Starter
{
  float:left;
  width:25%;
  height:40%;
  background-color:rgb(55, 128, 85);
  color: white;
  margin: 5% 1% 1% 4%;
  padding: 1% 1% 1% 1%;
  color: black;
  border-radius: 10% 10% 10% 10%;
}

#Starter img
{
  width:50%;
  margin-top: -5%;
}

<main>
    <div id="Starter">
      
     <div class="card_border">
        <div class="card_heading">
         <p> Starter Pack </p>
        </div>
        <div class="card_content">
        <input type="button" value="+" class=" button button1" id="addstarter"/>
        <a href="https://en.wikipedia.org/wiki/Entr%C3%A9e"><img src="images/starterr.png"></a>
        <input type="button" value="-" class=" button button2" id="minusstarter"/>
        <span class="tooltiptext">$5</span>
        </div>
      </div>  
    </div>