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'));
                    });

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

function copyToClipboard(element) {
    var $temp = $("<input>");
    $("body").append($temp);
    $temp.val($('span[id='+element+']').text()).select();
    document.execCommand("copy");
    $temp.remove();
}

你为什么不直接用这个代码，我不明白?

navigator.clipboard.writeText('text here...');

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>

2022年6月

更新:现在正确的方法是使用剪贴板API。

例如:

// get the text from the DOM Element: 
const textToCopy = document.querySelector('.content').innerText

// when someone clicks on the <a class="copy-text"> element 
// (which should be a <button>), execute the copy command:
document.querySelector('.copy-text').addEventListener('click' , ()=> {
  navigator.clipboard.writeText(textToCopy).then(
    function() {
      /* clipboard successfully set */
      window.alert('Success! The text was copied to your clipboard') 
    }, 
    function() {
      /* clipboard write failed */
      window.alert('Opps! Your browser does not support the Clipboard API')
    }
  )
})

就是这样。

如果你想看看在Clipboard API引入之前的解决方案(现在不是一个好的实践):

$('button.copyButton').click(function(){
    $(this).siblings('input.linkToCopy').select();      
    document.execCommand("copy");
});

HTML:

<button class="copyButton">click here to copy</button>
<input class="linkToCopy" value="TEXT TO COPY"
style="position: absolute; z-index: -999; opacity: 0;" />