有时候，特别是在Ajax请求返回数据时我们需要知道返回数据的结构，如果是Object，使用Alert是打印不出来的，使用Firebug中的 console 可以查看，我自己写了一个函数，有点像这个，有时候觉得使用console还不够直观，所以自己想办法写一个，不过现在支持的层级就三层，多了就不行了，多了就出现object。
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if(!window.debug){
window.debug = {};//选择一个自己的命名，千万别跟别人的冲突
};
debug.info = function(obj){
if (typeof _deBugStatus_ !== "undefined") {
return;
};
var version = "1.0",str = "",type,oLen = 0,ml=0,subStr = "",oimStr = "",aArr = "";
var st=document.createElement("style");
st.innerHTML = '' +
'.layer{font-family:Arial; font-size:14px; color:#333; line-height:150%; width:100%; height:100%; background:rgba(0,0,0,0.5); position:absolute; left:0; top:0; z-index:9999}' +
'.debug-box{width:900px; position:relative; left:50%; top:50%; margin-left:-450px; margin-top:-250px; background:white; box-shadow:0 0 50px rgba(0,0,0,0.5);}' +
'.debug-title{line-height:35px; padding: 0 10px; border-bottom:1px solid #AE0; background:#DED}' +
'.debug-names{width:20%; float:left; display:inline-block; *display:inline; *zoom:1; color:green; text-indent:5px}' +
'.debug-values{width:70%; float:right; color:orange}' +
'.debug-close{line-height:35px; position:absolute; right:0; top:0; color:#666; padding:0 10px; cursor:pointer}' +
'.uls{padding:0; margin:30px}' +
'.debug-clear{clear:both; line-height:0; height:0;}' +
'.debug-line{width:5%; float:left; color:blue}' +
'.debug-cs{overflow-y:auto; height:500px; padding-bottom:10px}' +
'#debugLayer li{border-bottom:1px solid #EEE;list-style:none; line-height:30px;}' +
'#debugLayer li:hover{background:#EDF4ED}' +
'.debug-obj-info{color:#666;}' +
'.debug-obj{font-weight:bold; color:green; margin:10px}';
var h = document.getElementsByTagName("head")[0];
h.appendChild(st);
if (typeof obj === "string") {
str = obj;
type = "String";
} else if (typeof obj === "object") {
if (obj instanceof Array) {
for (var i = 0, len = obj.length; i < len; i++) {
str += '<li><div class="debug-names">'+ i +'</div><div class="debug-line">=></div><div class="debug-values">' + obj[i] + '</div><div class="debug-clear"></div></li>';
}
type = "Array";
oLen = len;
} else {
for (var i in obj) {
if (typeof obj[i] == "object") {
if (obj[i]instanceof Array) {
for (var m = 0; m < obj[i].length; m++) {
if (typeof obj[i] == "object") {
if (obj[i]instanceof Array) {
var _a = "";
for (var k = 0; k < obj[i].length; k++) {
_a += '<div class="debug-names">' + k + '</div><div class="debug-line">=></div><div class="debug-values">' + obj[i][k] + '</div><div class="debug-clear"></div>';
}
aArr += '<div class="debug-names">' + m + '</div><div class="debug-line">=></div><div class="debug-values">' + _a + '</div><div class="debug-clear"></div>';
} else {
var _b = "";
for (var n in obj[i]) {
_b += '<div class="debug-names">' + n + '</div><div class="debug-line">=></div><div class="debug-values">' + obj[i][n] + '</div><div class="debug-clear"></div>';
}
aArr += '<div class="debug-names">' + m + '</div><div class="debug-line">=></div><div class="debug-values">' + _b + '</div>';
}
} else {
aArr += '<div class="debug-names">' + m + '</div><div class="debug-line">=></div><div class="debug-values">' + obj[i][m] + '</div><div class="debug-clear"></div>';
}
}
subStr += aArr;
str += '<li><div class="debug-names">' + i + '</div><div class="debug-line">=></div><div class="debug-values">' + subStr + '</div><div class="debug-clear"></div></li>';
} else {
for (var m in obj[i]) {
if (typeof obj[i][m] == "object") {
if (obj[i][m]instanceof Array) {
for (var j = 0; j < obj[i][m].length; j++) {
oimStr += '<div class="debug-names">' + j + '</div>' + '<div class="debug-line">=></div>' + '<div class="debug-values">' + obj[i][m][j] + '</div><div class="debug-clear"></div>';
}
subStr = oimStr;
} else {
for (var j in obj[i][m]) {
oimStr += '<div class="debug-names">' + j + '</div>' + '<div class="debug-line">=></div>' + '<div class="debug-values">' + obj[i][m][j] + '</div><div class="debug-clear"></div>';
}
subStr = oimStr;
}
} else {
subStr += '<div class="debug-names">' + m + '</div>' + '<div class="debug-line">=></div>' + '<div class="debug-values">' + obj[i][m] + '</div><div class="debug-clear"></div>';
}
}
str += '<li><div class="debug-names">' + i + '</div><div class="debug-line">=></div><div class="debug-values">' + subStr + '</div><div class="debug-clear"></div></li>';
}
} else {
str += '<li><div class="debug-names">' + i + '</div><div class="debug-line">=></div><div class="debug-values">' + obj[i] + '</div><div class="debug-clear"></div></li>';
}
ml++;
}
type = "Object";
oLen = ml;
}
} else if (obj instanceof Function) {
str = obj;
type = "Function";
}
result = '<ul class="uls"><li class="debug-obj-info">This is a <span class="debug-obj">'+type+'</span>info lenght:'+oLen+'</li>' + str + '</ul>';
var layer = document.createElement("div");
var box = document.createElement("div");
var title = document.createElement("div");
var content = document.createElement("div");
layer.setAttribute("class","layer");
layer.setAttribute("id", "debugLayer");
box.setAttribute("class","debug-box");
box.setAttribute("id", "debugBox");
title.setAttribute("id", "debugTitle");
title.setAttribute("class","debug-title");
layer.appendChild(box);
content.setAttribute("id", "debugContent");
content.setAttribute("class","debug-cs");
box.appendChild(title);
box.appendChild(content);
title.innerHTML = 'Debug Tools ' + version + '<span id="deBugClose" class="debug-close" title="Close Debug">close</span>';
content.innerHTML = result;
document.body.appendChild(layer);
document.getElementById("deBugClose").onclick = function () {
document.body.removeChild(layer);
}
layer.onclick = function(e){
if(document.all){
window.event.cancelBubble = true;
}else{
e.stopPropagation();
}
}
return _deBugStatus_ = 0;
}
?在body里面添加一个层，然后把信息输出来，很直观，个人觉得也很方便，自己经常使用。
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//测试一下效果 debug.info(navigator); //嘿嘿，是不是很酷