<script src="https://github.com/zenorocha/clipboard.js/blob/master/dist/clipboard.min.js"></script>

<!-- target -->
<input id="foo" value="hello,clipboard.">
<!-- trigger -->
<button class="btn1" data-clipboard-target="#foo">复制到剪贴板</button>
<script>new ClipboardJS('.btn1');</script>

<!-- target -->
<input id="foo" value="hello,clipboard.">
<!-- trigger -->
<button class="btn1">复制到剪贴板</button>
<script>
    new ClipboardJS('.btn1', {
        target: function(trigger) {
            return document.getElementById('foo');
        }
    });
</script>

<button id="btn1" data-clipboard-text="hello,clipboard.">复制到剪贴板</button>
<script>new ClipboardJS(document.getElementById('btn1'));</script>

<button id="btn1">复制到剪贴板</button>
<script>
    new ClipboardJS(document.getElementById('btn1'), {
        text: function(trigger) {
            return "hello,clipboard.";
        }
    });
</script>

<button class="btn1" style="display: none;" data-clipboard-text=""></button>
<script>new ClipboardJS(".btn1");</script>

<button id="todo">复制到剪贴板</button>

<script>
    $(document).ready(function(){
        $("#todo").click(function(){
            //todo...
            let text = (new Date()).getTime();
            
            $(".btn1").attr("data-clipboard-text", text);
            $(".btn1").click();
        });
    });
</script>

<button id="btn1" data-clipboard-text="hello,clipboard.">复制到剪贴板</button>

<script>
    var clipboard = new ClipboardJS(document.getElementById('btn1'));

    clipboard.on('success', function(e) {
        alert("复制成功！");
        e.clearSelection();
    });

    clipboard.on('error', function(e) {
        alert("复制失败，按 Ctrl+C 复制文字。");
    });
</script>