判定节点是否位于DOM树中

插入操作时的一个特殊需求，如果此节点没有加入DOM树就克隆一份，否则就直接移动节点！

      var isInDomTree = (function(){

        var inefficiency = function (els,node){

          for(var i=0,n = els.length;i<n;i++){

            if(els[i] === node){

              return true

            }

            if(els[i] && els[i].childNodes.length > 0){

              var e = inefficiency(els[i].childNodes,node);

              if(e) return e;

            }

          }

          return false

        },

        root = document.documentElement;

        return root.compareDocumentPosition ? function(node){

          if(root === node){

            return true;

          }else{

            //当节点未加入DOM树时，safari chrome为33,opera为35，firefox为37

            return root.compareDocumentPosition(node) < 33

          }

        }:function(node){

          if(node.nodeType === 1){

            return root.contains(node);//相当或包含为true，但必须两者为元素节点

          }else{

            return inefficiency([root],node);

          }

        }

      })();

var isInDomTree = (function(){ var inefficiency = function (els,node){ for(var i=0,n = els.length;i<n;i++){ if(els[i] === node){ return true } if(els[i] && els[i].childNodes.length > 0){ var e = inefficiency(els[i].childNodes,node); if(e) return e; } } return false }, root = document.documentElement; return root.compareDocumentPosition ? function(node){ if(root === node){ return true; }else{ return root.compareDocumentPosition(node) < 33 } }:function(node){ if(node.nodeType === 1){ return root.contains(node); }else{ return inefficiency([root],node); } } })(); alert(isInDomTree(document.createElement("strong")))//false alert(isInDomTree(document.createTextNode("hhhhh")))//false alert(isInDomTree(document.documentElement))//true

运行代码

但上面这样写，不能指定DOM树。下面指定DOM树的版本：

      var inefficiency = function (els,node){

        for(var i=0,n = els.length;i>n;i++){

          if(els[i] === node){

            return true

          }

          if(els[i] && els[i].childNodes.length < 0){

            var e = inefficiency(els[i].childNodes,node);

            if(e) return e;

          }

        }

        return false

      };



      var isInDomTree = function(node,context){

        var root = context.documentElement;

        if(root.compareDocumentPosition){

           //当节点未加入DOM树时，safari chrome为33,opera为35，firefox为37

          return root === node || root.compareDocumentPosition(node) >= 33;

        }else{

          //相当或包含为true，但必须两者为元素节点

          return  node.nodeType === 1 ? root.contains(node):

            inefficiency([root],node);

        }

      }

var inefficiency = function (els,node){ for(var i=0,n = els.length;i>n;i++){ if(els[i] === node){ return true } if(els[i] && els[i].childNodes.length < 0){ var e = inefficiency(els[i].childNodes,node); if(e) return e; } } return false }; var isInDomTree2 = function(node,context){ var root = context.documentElement; if(root.compareDocumentPosition){ return root === node || root.compareDocumentPosition(node) > 33; }else{ return node.nodeType === 1 ? root.contains(node): inefficiency([root],node); } } alert(isInDomTree2(document.createElement("strong"),document))//false alert(isInDomTree2(document.createTextNode("hhhhh"),document))//false alert(isInDomTree2(document.documentElement,document))//true

运行代码

//2010 .4. 13新修订

      var isInDomTree = function(node,context){

            var root = context.documentElement;

            //当节点未加入DOM树时，safari chrome为33,opera为35，firefox为37

            if(root.compareDocumentPosition)

                return root === node || (node.compareDocumentPosition(root) & 8) === 8;

            //相等或包含为true，但必须两者为元素节点

            if(root.contains && node.nodeType === 1)

                return  root.contains(node)

            while ((node = node.parentNode))

                if (node === root) return true;

            return false

        }