如何判斷元素是否為HTMLElement元素

我們常使用nodeType==1來判斷元素是否為HMTLElement元素。頁面上的元素都是節點(Node)，有元素節點(Element Node)、屬性節點(Attribute Node)、文字節點(Text Node)等。 w3c nodeType 的定義如下

const unsigned short ELEMENT_NODE = 1;

const unsigned short ATTRIBUTE_NODE = 2;

const unsigned short TEXT_NODE = 3;

const unsigned short CDATA_SECTION_NODE = 4;

const unsigned short ENTITY_REFERENCE_NODE = 5;

const unsigned short ENTITY_NODE = 6;

const unsigned short PROCESSING_INSTRUCTION_NODE = 7;

const unsigned short COMMENT_NODE = 8;

const unsigned short DOCUMENT_NODE = 9;

const unsigned short DOCUMENT_TYPE_NODE = 10;

const unsigned short DOCUMENT_FRAGMENT_NODE = 11;

const unsigned short NOTATION_NODE = 12;

但如果我們自訂的物件也包含nodeType屬性呢？如

複製代碼代碼如下:

var obj = {nodeType:1};

function isHTMLElement(obj){

if(obj.nodeType){

return obj.nodeType==1;

}

}

isHTMLElement(obj);//true

以上isHTMLElement(obj)回傳true，但obj明顯不是HTML節點元素。下面透過物件特性及try-catch語句來判斷。

複製代碼代碼如下:

function isHTMLElement(obj){

var d = document.createElement("div");

try{

d.appendChild(obj.cloneNode(true));

return obj.nodeType==1?true:false;

}catch(e){

return false;

}

}

var obj1 = {nodeType:1};

var obj2 = document.createTextNode("hello");

var obj2 = document.createElement("p");

isHTMLElement(obj1);//false

isHTMLElement(obj2);//false

isHTMLElement(obj3);//true

對於window和document還要特別處理下

複製代碼代碼如下:

function isHtmlControl(obj) {

var d = document.createElement("div");

try{

d.appendChild(obj.cloneNode(true));

return obj.nodeType==1 ? true : false;

}catch(e){

return obj==window || obj==document;

}

}