JavaScript利用DOM给页面添加内容

自定义一个log函数,输出传入函数的对象或者信息.
Log.js
// JScript source code
function
log(category, message, object) {
// If this category is explicitly disabled, do nothing
if
(log.options[category + "Disabled
"]) return
;
// Find the container
var
id = category + "_log
";
var
c = document
.getElementById(id);
// If there is no container, but logging in this category is enabled,
// create the container.
if
(!c && log.options[category + "Enabled
"]) {
c = document
.createElement("div
");
c.id = id;
c.className = "log
";
document
.body.appendChild(c);
}
// If still no container, we ignore the message
if
(!c) return
;
// If timestamping is enabled, add the timestamp
if
(log.options.timestamp)
message = new
Date
() + ":
" + (message ? message : "");
// Create a element to hold the log entry
var
entry = document
.createElement("div
");
entry.className = category + "_message
";
if
(message) {
// Add the message to it
entry.appendChild(document
.createTextNode(message));
}
if
(object && typeof
object == "object
") {
entry.appendChild(log.makeTable(object, 0));
}
// Finally, add the entry to the logging container
c.appendChild(entry);
}
// Create a table to display the properties of the specified object
log.makeTable = function
(object, level) {
// If we've reached maximum recursion, return a Text node instead.
if
(level > log.options.maxRecursion)
return
document
.createTextNode(object.toString
());
// Create the table we'll be returning
var
table = document
.createElement("table
");
table.border = 1;
// Add a Name|Type|Value header to the table
var
header = docum