javascript falsy value

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4     <title></title>
 5     <script type="text/javascript">
 6         window.onload = function () {
 7             for (var f = document.createElement("table"), a = [null, "", " ", 0, "0", void 0, NaN, !1], e, c, b = 0; b <= a.length; b++)if (e = document.createElement("tr"), f.appendChild(e), 0 == b) {
 8                 e.className = " title";
 9                 for (var d = 0; d <= a.length; d++)0 == b && 0 == d ? (c = document.createElement("td"), c.innerHTML = "Compare") : (c = document.createElement("td"), c.innerHTML = "string" === typeof a[d - 1] ? '"' + a[d - 1] + '"' : a[d - 1] + ""), e.appendChild(c)
10             } else for (d = 0; d <= a.length; d++)0 == d ? (c = document.createElement("td"), c.innerHTML = "string" === typeof a[b -
11                     1] ? '"' + a[b - 1] + '"' : a[b - 1] + "", e.appendChild(c), c.className = " title") : (c = document.createElement("td"), c.innerHTML = a[b - 1] == a[d - 1], e.appendChild(c));
12             a = f.childNodes;
13             for (b = 0; b < a.length; b++)a[b].className || (a[b].className = 0 == b % 2 ? "odd" : "even"), a[b].oldClassName = a[b].className, a[b].onmouseover = function () {
14                 this.className += " highlight"
15             }, a[b].onmouseout = function () {
16                 this.className = this.oldClassName
17             }, document.getElementsByTagName("div")[0].appendChild(f)
18         };
19 
20     </script>
21     <style>
22             /*  html{
23                   text-align: center;
24               }*/
25         table {
26             width: 60%;
27             font-family: Arial, sans-serif;
28             text-align: left;
29             margin: 0 auto; /* 这里主要作用是设置左右margin为auto，这样就能在让容器居中，否则在FF中只是文字在容器中居中.容器继承了body的text-align:center ，文字也居中了 */
30             /*border-color: #000000;*/
31             border: #334455 solid thin;
32         }
33 
34         body {
35             text-align: center;
36             background: #666677;
37         }
38 
39         .odd {
40             background-color: #cccccc;
41         }
42 
43         .even {
44             background-color: #c6eccb;
45         }
46 
47         .title {
48             background-color: #ffc353;
49         }
50 
51         .highlight {
52             background-color: #eecc88;
53             font-style: italic;
54             font-family: fantasy;
55         }
56 
57         td {
58             font-family: Helvetica, serif;
59             font-size: 12px;
60             width: 50px;
61         }
62 
63         tr {
64             line-height: 1em;
65         }
66 
67         tr.title>td {
68             text-align: center;
69             font-size: 14px;
70             font-weight: bold;
71             font-style: italic;
72             line-height: 1.5em;
73         }
74 
75         p {
76             font: italic normal bold 14px normal;
77         }
78 
79         h1 {
80             font: italic normal bold 20pt "Times New Roman";
81         }
82     </style>
83 
84 </head>
85 <body>
86 <div>
87     <h1>hello world</h1>
88 
89     <p>注意:在if()判断体内自动转为false的是:0,'',undefined,null,NaN。而' ','0'在if()判断体中为true</p>
90 </div>
91 </body>
92 </html>