var content = "需要复制的内容";
try {
    var save = function (e) {
        e.clipboardData.setData('text/plain', content);
        e.preventDefault();
    };
    document.addEventListener('copy', save);
    document.execCommand('copy');
    confirm('复制内容成功');
} catch (error) {
    confirm('复制内容失败');
}