Native JS implements the copy text function

	<input type="text">
    <button onClick="copyFn()"> Click replication </button>
    <script>
        function copyFn(){
    
            let txt=document.getElementsByTagName('input')[0].value;
            copy(txt);
        }

        function copy(item){
    
            let span=document.createElement('span');
            let Text=document.createTextNode(item);
            span.appendChild(Text);
            document.body.appendChild(span);
            window.getSelection().selectAllChildren(span);
            document.execCommand ("Copy");
            document.body.removeChild(span);
        }
    </script>

establish html Elements , because execCommand You must copy the label elements that exist on the page , Wait until the text is copied to the clipboard , Remove element again .