检查布尔值 - 检查布尔对象是 true 还是 false。

<script>

  var b1 = new Boolean(0);

  var b2 = new Boolean(1);

  var b3 = new Boolean("");

  var b4 = new Boolean(null);

  var b5 = new Boolean(NaN);

  var b6 = new Boolean("false");

  document.write("0 为布尔值 " + b1 + "<br>");

  document.write("1 为布尔值 " + b2 + "<br>");

  document.write("空字符串是布尔值 " + b3 + "<br>");

  document.write("null 是布尔值 " + b4 + "<br>");

  document.write("NaN 是布尔值 " + b5 + "<br>");

  document.write("字符串'false' 是布尔值" + b6 + "<br>");

</script>