这里是HTML代码

    <input id="result" style="width:300px"/>some example text
    <button onclick="copyToClipboard('result')">Copy P1</button>
    <input type="text" style="width:400px" placeholder="Paste here for test" />

JS代码:

     function copyToClipboard(elementId) {

                      // Create a "hidden" input
                      var aux = document.createElement("input");

                      aux.setAttribute("value", document.getElementById(elementId).value);
                      // Append it to the body
                      document.body.appendChild(aux);
                      // Highlight its content
                      aux.select();
                      // Copy the highlighted text
                      document.execCommand("copy");
                      // Remove it from the body
                      document.body.removeChild(aux);
                    }

<p style="color:wheat;font-size:55px;text-align:center;">How to copy a TEXT to Clipboard on a Button-Click</p>
    
    <center>
    <p id="p1">Hello, I'm TEXT 1</p>
    <p id="p2">Hi, I'm the 2nd TEXT</p><br/>
    
    <button onclick="copyToClipboard('#p1')">Copy TEXT 1</button>
    <button onclick="copyToClipboard('#p2')">Copy TEXT 2</button>
      
    </center>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">
<script>
    function copyToClipboard(element) {
      var $temp = $("<input>");
      $("body").append($temp);
      $temp.val($(element).text()).select();
      document.execCommand("copy");
      $temp.remove();
    }
</script>

2023年1月

从2023年开始，你应该使用剪贴板Api。

navigator.clipboard.writeText('text here you want to copy').then(function () {
    alert('It worked! Do a CTRL - V to paste')
}, function () {
    alert('Failure to copy. Check permissions for clipboard')
});

这里是关于与剪贴板交互的更多信息

这是一个优雅的Javascript解决方案

<input type="text" value="Foo Bar" id="your_input">
<button onclick="copy()">Copy text</button>

<script type="application/javascript">
function copy() {
  var copiedtext = document.getElementById("your_input");
  copiedtext.select();
  copiedtext.setSelectionRange(0, 99999); //for mobile devices
  navigator.clipboard.writeText(copiedtext.value);
  alert("You just copied " + copiedtext.value);
}
</script>

我刚才正在做，我只是想知道有没有比我更好的方法，但是没有。

你可以使用我的代码，它复制文本并显示一个工具提示。

Head

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
<link href="https://cdn.jsdelivr.net/npm/remixicon@2.2.0/fonts/remixicon.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js" integrity="sha512-894YE6QWD5I59HgZOGReFYm4dnWc1Qt5NtvYSaNcOP+u1T9qYdvdihz0PPSiiqn/+/3e7Jo4EaG7TubfWGUrMQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

Body

<div class="alert alert-primary alert-dismissible mb-0 py-1" role="alert" id="liveAlert">
    <div class="container d-flex justify-content-between">
      <button type="button" class=" btn align-self-center ms-4 copytext" data-bs-toggle="tooltip" data-bs-placement="top" title=""><strong>Good news!</strong>  You just got 10% off, use your coupon <span class="fw-bold bg-secondary text-white px-2 maintext">store10off</span>. <i class="ri-file-copy-line"></i></button>
      <button type="button" class="btn align-self-center" data-bs-dismiss="alert" aria-label="Close"><strong class="fw-bold fs-4"><i class="ri-close-fill"></i></strong></button>
    </div>
    </div>

函数

<script>
    $('.copytext').click(function(){
        var thistooltip = $(this);
        var thistext = $(this).children('.maintext').text();
        navigator.clipboard.writeText(thistext);
        $(this).attr('title','copied');
        setTimeout(function(){$(thistooltip).tooltip("toggle");}, 800);
    });
</script>

这是复制内容的最简单方法

 <div id="content"> Lorepm ispum </div>
 <button class="copy" title="content">Copy Sorce</button>

function SelectContent(element) {
                        var doc = document
                            , text = doc.getElementById(element)
                            , range, selection
                        ;    
                        if (doc.body.createTextRange) {
                            range = document.body.createTextRange();
                            range.moveToElementText(text);
                            range.select();
                        } else if (window.getSelection) {
                            selection = window.getSelection();        
                            range = document.createRange();
                            range.selectNodeContents(text);
                            selection.removeAllRanges();
                            selection.addRange(range);

                        }
                         document.execCommand('Copy');
                    }
                    $(".copy").click(function(){

                         SelectContent( $(this).attr('title'));
                    });