JavaScript DOM 编程艺术 公用方法

function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != ‘function‘) {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}

function highlightRows() {
  if(!document.getElementsByTagName) return false;
  var rows = document.getElementsByTagName("tr");
  for (var i=0; i<rows.length; i++) {
    rows[i].onmouseover = function() {
      this.style.fontWeight = "bold";
    }
    rows[i].onmouseout = function() {
      this.style.fontWeight = "normal";
    }
  }
}
addLoadEvent(highlightRows);

function stripeTables() {
  if (!document.getElementsByTagName) return false;
  var tables = document.getElementsByTagName("table");
  for (var i=0; i<tables.length; i++) {
    var odd = false;
    var rows = tables[i].getElementsByTagName("tr");
    for (var j=0; j<rows.length; j++) {
      if (odd == true) {
        addClass(rows[j],"odd");
        odd = false;
      } else {
        odd = true;
      }
    }
  }
}
function addClass(element,value) {
  if (!element.className) {
    element.className = value;
  } else {
    newClassName = element.className;
    newClassName+= " ";
    newClassName+= value;
    element.className = newClassName;
  }
}

function moveElement(elementID,final_x,final_y,interval) {
  if (!document.getElementById) return false;
  if (!document.getElementById(elementID)) return false;
  var elem = document.getElementById(elementID);
  if (elem.movement) {
    clearTimeout(elem.movement);
  }
  if (!elem.style.left) {
    elem.style.left = "0px";
  }
  if (!elem.style.top) {
    elem.style.top = "0px";
  }
  var xpos = parseInt(elem.style.left);
  var ypos = parseInt(elem.style.top);
  if (xpos == final_x && ypos == final_y) {
    return true;
  }
  if (xpos < final_x) {
    var dist = Math.ceil((final_x - xpos)/10);
    xpos = xpos + dist;
  }
  if (xpos > final_x) {
    var dist = Math.ceil((xpos - final_x)/10);
    xpos = xpos - dist;
  }
  if (ypos < final_y) {
    var dist = Math.ceil((final_y - ypos)/10);
    ypos = ypos + dist;
  }
  if (ypos > final_y) {
    var dist = Math.ceil((ypos - final_y)/10);
    ypos = ypos - dist;
  }
  elem.style.left = xpos + "px";
  elem.style.top = ypos + "px";
  var repeat = "moveElement(‘"+elementID+"‘,"+final_x+","+final_y+","+interval+")";
  elem.movement = setTimeout(repeat,interval);
}
function positionMessage() {
  if (!document.getElementById) return false;
  if (!document.getElementById("message")) return false;
  var elem = document.getElementById("message");
  elem.style.position = "absolute";
  elem.style.left = "50px";
  elem.style.top = "100px";
  moveElement("message",125,25,20);
}
addLoadEvent(positionMessage);

function insertAfter(newElement,targetElement) {
  var parent = targetElement.parentNode;
  if (parent.lastChild == targetElement) {
    parent.appendChild(newElement);
  } else {
    parent.insertBefore(newElement,targetElement.nextSibling);
  }
}

function addClass(element,value) {
  if (!element.className) {
    element.className = value;
  } else {
    newClassName = element.className;
    newClassName+= " ";
    newClassName+= value;
    element.className = newClassName;
  }
}

function getHTTPObject() {
  if (typeof XMLHttpRequest == "undefined")
    XMLHttpRequest = function () {
      try { return new ActiveXObject("Msxml2.XMLHTTP.6.0"); }
        catch (e) {}
      try { return new ActiveXObject("Msxml2.XMLHTTP.3.0"); }
        catch (e) {}
      try { return new ActiveXObject("Msxml2.XMLHTTP"); }
        catch (e) {}
      return false;
  }
  return new XMLHttpRequest();
}

function displayAjaxLoading(element) {
  while (element.hasChildNodes()) {
      element.removeChild(element.lastChild);
  }
  var content = document.createElement("img");
  content.setAttribute("src","images/loading.gif");
  content.setAttribute("alt","Loading...");
  element.appendChild(content);
}

function submitFormWithAjax( whichform, thetarget ) {
  var request = getHTTPObject();
  if (!request) { return false; }

  displayAjaxLoading(thetarget);

  var dataParts = [];
  var element;
  for (var i=0; i<whichform.elements.length; i++) {
    element = whichform.elements[i];
    dataParts[i] = element.name + ‘=‘ + encodeURIComponent(element.value);
  }
  var data = dataParts.join(‘&‘);

  request.open(‘POST‘, whichform.getAttribute("action"), true);
  request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

  request.onreadystatechange = function () {
    if (request.readyState == 4) {
        if (request.status == 200 || request.status == 0) {
          var matches = request.responseText.match(/<article>([\s\S]+)<\/article>/);
          if (matches.length > 0) {
            thetarget.innerHTML = matches[1];
          } else {
            thetarget.innerHTML = ‘<p>Oops, there was an error. Sorry.</p>‘;
          }
        } else {
          thetarget.innerHTML = ‘<p>‘ + request.statusText + ‘</p>‘;
        }
    }
  };
  request.send(data);
  return true;
};

submitFormWithAjax(this, document.getElementsByTagName(‘article‘)[0]);