JavaScript 实现将 Input 或 Textarea 内容复制到剪贴板

function copyToClipboard(elem) {
// create hidden text element, if it doesn't already exist
var targetId = "_hiddenCopyText_";
var isInput = elem.tagName === "INPUT" || elem.tagName === "TEXTAREA";
var origSelectionStart, origSelectionEnd;
if (isInput) {
// can just use the original source element for the selection and copy
target = elem;
origSelectionStart = elem.selectionStart;
origSelectionEnd = elem.selectionEnd;
} else {
// must use a temporary form element for the selection and copy
target = document.getElementById(targetId);
if (!target) {
var target = document.createElement("textarea");
target.style.position = "absolute";
target.style.left = "-9999px";
target.style.top = "0";
target.id = targetId;
document.body.appendChild(target);
}
target.textContent = elem.textContent;
}
// select the content
var currentFocus = document.activeElement;
target.focus();
target.setSelectionRange(0, target.value.length);
// copy the selection
var succeed;
try {
succeed = document.execCommand("copy");
} catch(e) {
succeed = false;
}
// restore original focus
if (currentFocus && typeof currentFocus.focus === "function") {
currentFocus.focus();
}
if (isInput) {
// restore prior selection
elem.setSelectionRange(origSelectionStart, origSelectionEnd);
} else {
// clear temporary content
target.textContent = "";
}
return succeed;
}

copyToClipboard(document.getElementById("name"));