客户端JavaScript只能为网页所在的域设置cookie。

您引用的示例使用 HTTP标头设置cookie ，而不是JavaScript。

I am trying to set cookie to domain same as src of js file.

Scenario: In www.xyz.com html, I have included js file from qwe.com as below

<script type="application/javascript" src="http://qwe.com/b.js"></script>

From this b.js, i want to create cookie with domain set to .qwe.com. I am setting cookie with following function

function createCookie(name, value, days) {
    if (days) {
      var date = new Date();
      date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
      var expires = "; expires=" + date.toGMTString();
    } else {
      var expires = "";
    }
    document.cookie = name+"="+value+expires+";domain=.qwe.com"+"; path=/;";
  }

With above code I am unable to set cookie. Example: www.flipkart.com-> Check cookies in resources tab of developer console-> .scorecardresearch.com and .doubleclick.net are able to set cookie

I want to do same. Can someone please share solution for this? Real working solution. I have tried multiple solutions by doing Google search. It didn't work.

Client side JavaScript can set cookies only for the domain the webpage is hosted on.

The examples you cite use HTTP headers to set cookies, not JavaScript.