onclick 修饰符函数引用变量而不是使用变量值 (JavaScript)

Question

(Edit: Someone asked for where trueName is defined in relation to the loop, so I included it in the code sample. relPath is defined in the function parameter)

I have a forEach loop that is meant to clone a template and set an onclick function to open a link for each clone. From the code sample below, you can see that I have 2 variables - relPath and trueName - that are supposed to form part of the parameter passed to the function:

function showDirectoryItems(relPath, data){
    Object.keys(data).forEach((item)=>{
        nameSplit = item.split(">>");
        trueName = nameSplit[0];
        ...
        if (data[item]=="file"){
            clone.getElementById("name").onclick = function() {downloadFile(relPath+'/'+trueName)};
        ...

So in theory, one of the clones would have an onclick function of (for example) downloadFile('files/test1.txt') , another would have downloadFile('files/test2.mp3') , etc.

However, when I run the code, the onclick functions in all of the clones seemed to link to the same path of the last item. I checked the code and realised that the onclick functions used variable references instead of an absolute value (ie, instead of something like 'files'+'/'+'aaa.txt' , it was relPath+'/'+trueName ):

As such, how do I set the onclick function to take in the absolute value of these variables during the forEach loop, instead of a variable reference ?

Answer 1

Managed to fix the problem in the end by changing the line where trueName is defined:

trueName = nameSplit[0]

and adding var in front of trueName to declare it as a variable:

var trueName = nameSplit[0]

What I'm guessing is causing the issue, as per this answer to another question, is that because I did not put var when declaring the variable, the code treated trueName as a implicit global, thus causing the onclick function to reference the variable name instead of getting the variable's value directly.

Answer 2

Hey your question may like this:

HTML:

<div>1</div>
<div>2</div>
<div>3</div>
<div>4</div>
<div>5</div>
<div>6</div>
<div>7</div>
<div>8</div>
<div>9</div>

JS:

document.querySelectorAll("div").forEach((e) => {
  name123 = e.innerText;
  e.onclick = function () {
    alert(name123);
  };
});

Click any of them will show 9, the last element;

Solution:

Move the [nameSplit, trueName] to onClick scope.

In my example like:

document.querySelectorAll("div").forEach((e) => {
  e.onclick = function () {
   name123 = e.innerText;
   alert(name123);
  };
});