js打开新的链接下载文件

var p =params.join("&");
var a = document.createElement('a');
a.href = 'report/exportpubcount.do'+p;
a.target = '_blank';
a.id='exppub';
document.body.appendChild(a);
var alink = document.getElementById('exppub');
alink.click();
alink.parentNode.removeChild(a);