javascript – 为什么document.execCommand(“copy”)在我的chrome扩展的内容脚本中不起作用？

参见英文答案 > Why is document.execCommand(“paste”) not working in Google Chrome?6个
我想从我正在创建的chrome扩展中将一些数据写入clipborad.
在清单文件中,我赋予了clipboardRead和clipboardWrite的权限.

我使用这个功能,我找到了here

但它不起作用.好像是“document.execCommand(‘copy’);”无法工作.

我在内容脚本中写下所有这些代码.

谢谢
表现：

{
    "manifest_version":2,"name":"easyCopy","description":"just a small toll","version":"1.0.0","permissions":[
        "clipboardWrite","http://*/*","clipboardRead"
    ],"content_scripts":[
        {
            "matches":["http://*/*"],"js":["jquery-1.9.1.min.js","main_feature.js"]
        }
    ],"BACkground":{
        "persistent":false,"page":"BACkground.html"
    }
}

@H_418_4@main_feature.js：

copyOrderId();
function copyOrderId() {
    $(".order-num").click(function () {
        var curOrderNum = $(this).text();
        copyTextToClipboard(curOrderNum);
//        chrome.extension.sendmessage({method:"copy",content:curOrderNum},function (responsE) {
//            clog(responsE);
//        });
    });


}

function copyTextToClipboard(text) {
    var copyFrom = $('<textarea/>');
    copyFrom.text(text);
    $('body').append(copyFrom);
    copyFrom.SELEct();
    document.execCommand('copy',truE);
    copyFrom.remove();

}
function clog(messagE) {
    console.log(messagE);
}

BACkground.html只是一个基本的html主体的空白页面.