如何在javascript的setAttribute()方法中向函数添加参数

Question

在 javascript 中，我正在创建新的图像标签，并使用 setAttribute() 方法向它们添加属性，但我发现如果添加一个 onclick 事件并添加一个函数，则无法为其设置参数，如下所示

count = 0; //Will be the number that will go into parameter for function
function start() {
imageTag = document.createElement("IMG"); //Creates image tag
imageTag.setAttribute("src", "popo.jpg"); //sets the image tags source
count++; //as the start function keeps getting called, count will increase by 1 and the parameter for each function in each individual image tag will increase by one
imageTag.setAttribute("onclick", "disappear(count)"); //this will add the onclick attribute with the function disappear() and the parameter inside which will be a number that will increase as the start function is called again and the image tag is called again *ERROR*
document.body.appendChild(imageTag); //appends the image tag created
}

问题是，当每个新的图像标签被创建时，它实际上只是创建

<img src = "popo.jpg" onclick = "disappear(count)"/>

我想让它更像

<img src = "popo.jpg" onclick = "disappear('1')"/>
<img src = "popo.jpg" onclick = "disappear('2')"/> //and so on...

Answer 1

在函数中添加计数作为参数，而不是字符串。

count = 0; //Will be the number that will go into parameter for function
function start() {
    imageTag = document.createElement("IMG"); //Creates image tag
    imageTag.setAttribute("src", "popo.jpg"); //sets the image tags source
    count++; //as the start function keeps getting called, count will increase by 1 and the parameter for each function in each individual image tag will increase by one
    imageTag.setAttribute("onclick", "disappear("+count+")"); //this will add the onclick attribute with the function disappear() and the parameter inside which will be a number that will increase as the start function is called again and the image tag is called again *ERROR*
    document.body.appendChild(imageTag); //appends the image tag created
}

Answer 2

而不是添加点击事件作为属性添加它使用addEventListener

imageTag.addEventListener("click", disappear.bind(null, count));

Bind将count在调用时对函数可用。

然后创建一个消失函数

function disappear(ID){
  alert(ID); // This should give the count.
}

Answer 3

由于您使用setAttribute，您正在设置事件处理程序内容属性。相应的事件处理程序设置为内部原始未编译处理程序。该代码的范围将是

• 全局对象
• 文件
• 表单所有者（如果有）
• 元素（如果有）

如果您的count变量在这些范围中的任何一个范围内都不可用，则它将不起作用。即使它可用，由于您不断增加它，使用的值将是修改后的值。

但是你不想那样。相反，您可以：

• 在未编译的处理程序中写入变量：

  imageTag.setAttribute("onclick", "disappear(" + count + ")");
  

• 使用事件处理程序 IDL 属性，例如

  var localCount = count; // Using a local copy in case `count` is modified
  imageTag.onclick = function() {
      disappear(localCount);
  };