javascript - 仅向进入我网站的 20% 的人显示 div

Question

我想只显示我网站 20% 流量的 div，所以我做了这样的逻辑:

var div = (Math.floor(Math.random() * 100) + 1) > 20 ? true : false;
if (div)
  // don't show
else
  // show

但我认为这并不准确，是吗？

谢谢。

Answer 1

考虑到所有的随机性，需要有足够大的样本量才能显示正态分布。正如您所看到的，您获得的访问者越多，该函数就越接近 20%。

function visitors(n) {
  var visited = 0;
  for (var i = 0; i < n; i++)
    visited += (Math.floor(Math.random() * 100) + 1) > 20 ? 0 : 1;
  console.log("Out of " + n + " visitors, " + visited + " were shown the div. (" + visited / n * 100 + "%)");
}

[1, 10, 100, 1000, 10000, 100000, 1000000].forEach(x => visitors(x));

如Radmation但是，提到过，对于较少数量的访问者，使用服务器将使您更接近 20%。

I wouldnt use client side logic for this but server side logic. You could literally increment a server side variable and every time it gets to 5 reset it and tell the client to show the div. Of course start with 1 in this case. If you need to be exact at least -> you could use ajax as well to get the counters value - if you run into multiple requests at once.