Copy复制命令兼容各种浏览器（等同于触发Ctrl+C或者Command⌘+C）

/*复制命令兼容各种浏览器*/
function copy(copyContent, isAlert, maxLength) {
        if (window.clipboardData) {
            window.clipboardData.setData("Text", copyContent);
        }
        if (document.execCommand) {
            var copyTextarea = document.createElement("textarea");
            document.body.appendChild(copyTextarea);
            copyTextarea.innerText = copyContent;
            copyTextarea.select();
            document.execCommand("Copy");
            copyTextarea.parentNode.removeChild(copyTextarea);
        }
        if (isAlert) {
            if (typeof isAlert === "function") {
                isAlert(copyContent);
            } else {
                maxLength && (copyContent.length > maxLength) && (copyContent = copyContent.substr(0, maxLength) + "…");
                alert(`“${copyContent}”复制成功！`);
            }
        }
}