Simple encapsulation of JS DOM query instance code _javascript tips

Recently has been gnawing Rhino book, feeling, so wrote a simple JS Dom query

$ = function (val) {
    switch (val.charat (0)) {case
      ' # ': Return
        document.getElementById (val.substring (1)); C4/>break;
      Case '. ':
        val = val.replace ('. ', ');
        if (document.getelementsbyclassname) return
          Document.getelementsbyclassname (val);
        else {
          var obj = document.getelementsbytagname (' * '), len = obj.length,arr=[];

          for (Var i=0;i<len;i++) {
            if (Obj[i].classname = = val) {
              arr[arr.length] = obj[i]
            ;
          }

          return arr;
        }
        break;
      Default:
        if (Document.getelementsbyname (val). length > 0) return
          Document.getelementsbyname (val);
        else return 
          document.getElementsByTagName (val); 
    }
  

Such an implementation, in the future call ID, just $ (' #idname '), class when $ ('. ClassName '), tagname and name are all made a simple judgment, are directly to pass $ (' name '), I tried, feel OK.

Above this simple package JS Dom Query Instance code is a small series to share all the content, hope to give you a reference, but also hope that we support cloud habitat community.