如何在每次调用函数时在JavaScript中创建唯一的ID？

Question

这里的功能：

function addAttachment() { 
    if (allowed_attachments <= 0) 
     return alert("', $txt['more_attachments_error'], '"); 

    document.getElementById("uploadBtn").onchange = function() {             
     document.getElementById("uploadFile").value = this.value; 
    }; 


    setOuterHTML(document.getElementById("moreAttachments"), 
     \'<div class="upload_attachment">\ 
      <input id="uploadFile" placeholder="File">\ 
      <label class="custom-file-input">\ 
       <input type="file" id="uploadBtn" name="attachment[]">\ 
      </label></div><span id="moreAttachments">\ 
     </span>\'); 
    allowed_attachments = allowed_attachments - 1; 
    return true; 
} 

UploadBtn和UploadFile需要是唯一的每次，我该怎么办呢？我真的坚持

Answer 1

使用日期对象的方法现在Date.now()

Answer 2

使用一个全局对象（满分addAttachement范围）是这样的：

var UNIQUE_ID = 0; // the ID counter (will be incremented each time a new item is created so it'll be unique) 

function addAttachment() { 
    if (allowed_attachments <= 0) 
     return alert("', $txt['more_attachments_error'], '"); 

    document.getElementById("uploadBtn").onchange = function() {             
     document.getElementById("uploadFile").value = this.value; 
    }; 

    UNIQUE_ID++; // increment the ID counter 

    setOuterHTML(document.getElementById("moreAttachments"), 
     '<div class="upload_attachment">\ 
      <input id="uploadFile' + UNIQUE_ID + '" placeholder="File">\ 
      <label class="custom-file-input">\ 
       <input type="file" id="uploadBtn' + UNIQUE_ID + '" name="attachment[]">\ 
      </label></div><span id="moreAttachments' + UNIQUE_ID + '">\ 
     </span>'); 
    allowed_attachments = allowed_attachments - 1; 
    return true; 
}