javascript DOM编程艺术书中的一些工具函数

<script>
在文档完全加载后想运行某个函数，用下面的函数addLoadEvent
function addLoadEvent(func){
  var oldonload = window.onload;
    if(typeof window.onload !='function'){
      window.onload = func;
    }else{
      window.onlad = function(){
          oldonload();
            func();
        }
    }
}

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

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

highlightPage

function highlightPage(){
  if(!document.getElementsByTagName) return false;
    if(!document.getElementById) return false;
    var headers = document.getElementsByTagName('header');
    if(headers.length == 0) return false;
    var navs = headers[0].getElementsByTagName('nav');
    if(navs.length == 0) return false;
    var links = navs[0].getElementsByTagName('a');
    for(var i=0; i<links.length; i++){
      linkurl = links[i].getAttribute('href');
        if(window.location.href.indexOf(linkurl)!=-1){
          links[i].className = "now";
            var linktext = links[i].lastChild.nodeValue.toLowerCase();
            document.body.setAttribute("id",linktext);
        }
    }
}
addLoadEvent(highlightPage);

动画函数

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);
}
var xpos = parseInt(elem.offsetLeft);
var ypos = parseInt(elem.offsetTop);
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);
}
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 prepareSlideshow(){
  if(!document.getElementsByTagName) return false;
    if(!document.getElementById) return false;
    if(!document.getElementById("intro")) return false;
    var intro = document.getElementById("intro");
    var slideshow = document.createrElement("div");
    slideshow.setAttribute("id","slideshow");
    var frame = document.createElement("img");
    frame.setAttribute("src","images/frame.gif");
    frame.setAttribute("alt","");
    frame.setAttribute("id","frame");
    slideshow.appendChild(frame);
    var preview = document.createElement("img");
    preview.setAttribute("src","images/slideshow.gif");
    preview.setAttribute("alt","a glimpse of what awaits you");
    preview.setAttribute("id","preview");
    slideshow.appendChild(preview);
    insertAfter(slideshow,intro);
    var links = document.getElementsByTagName("a");
    var destination;
    for(var i=0; i<links.length; i++){
      links[i].onmouseover = function(){
          destination = this.getAttribute("href");
            if(destination.indexOf("index.html")!=-1){
              moveElement("preview",0,0,5);
            }
            if(destination.indexOf("about.html")!=-1){
              moveElement("preview",-150,0,5);
            }
            if(destination.indexOf("photos.html")!=-1){
              moveElement("preview",-300,0,5);
            }
            if(destination.indexOf("live.html")!=-1){
              moveElement("preview",-450,0,5);
            }
            if(destination.indexOf("contact.html")!=-1){
              moveElement("preview",-600,0,5);
            }
        }
    }
}
addLoadEvent(prepareSlideshow);

function showSection(id){
  var sections = document.getElementsByTagName("section");
    for(var i=0; i<sections.length; i++){
      if(sections[i].getAttribute("id")!=id){
          sections[i].style.display = "none";
        }else{
          sections[i].style.display = "block"
        }
    }
}

function prepareInternalnav(){
  if(!document.getElementsByTagName) return false;
    if(!document.getElementById) return false;
    var articles = document.getElementsByTagName("article");
    if(articles.length ==0) return false;
    var navs = articles[0].getElementsByTagName("nav");
    if(navs.length ==0) return false;
    var nav = navs[0];
    var links = nav.getElementsByTagName("a");
    for(var i=0; i<links.length; i++){
      var sectionId = links[i].getAttribute("href").split("#")[1];
        if(!document.getElementById(sectionId)) continue;
        document.getElementById(sectionId).style.display = "none";
        links[i].destination = sectionId;
        links[i].onclick = function(){
          showSection(this.destination);
            return false;
        }
    }
}
addLoadEvent(prepareInternalnav);

//表格隔行变色
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(row[j],"odd");
                odd = false;
            }else{
              odd = true;
            }
        }
    }
}
//表格鼠标移上变色
function highlightrows(){
  if(!document.getElementsByTagName) return false;
    var rows = document.getElementsByTagName("tr");
    for(var i=0; i<rows.length; i++){
      rows[i].oldClassName = rows[i].className;
        rows[i].onmouseover = function(){
          addClass(this,"highlight");
        }
        rows[i].onmouseout = function(){
          this.className = this.oldClassName;
        }
    }
}
//提取页面中的注释
function displayabbreviations(){
  if(!document.getElementsByTagName || !document.createElement || !document.createTextNode) return false;
    var abbreviations = document.getElementsByTagName("abbr");
    if(abbreviations.length<1) return false;
    var defs = new Array();
    for(var i=0; i<abbreviations.length; i++){
      var current_abbr = abbreviations[i];
        if(current_abbr.childNodes.length<1) continue;
        var definition = current_abbr.getAttribute("title");
        var key = current_abbr.lastChild.nodeValue;
        defs[key] = definition;
    }
    
    var dlist = document.createElement("dl");
    for(key in defs){
      var definition = defs[key];
        var dtitle = document.createElement("dt");
        var dtitle_text = document.createTextNode(key);
        dtitle.appendChild(dtitle_text);
        var ddesc = document.createElement("dd");
        var ddesc_text = document.createTextNode(definition);
        ddesc.appendChild(ddesc_text);
        dlist.appendChild(dtitle);
        dlist.appendChild(ddesc);
    }
    if(dlist.childNodes.length<1) return false;
    var header = document.createElement("h3");
    var header_text = document.createTextNode("abbreviations");
    header.appendChild(header_text);
    var articles = document.getElementsByTagName("article");
    if(articles.length == 0) return false;
    var container = articles[0];
    container.appendChild(header);
    container.appendChild(dlist);
}
addLoadEvent(stripetables);
addLoadEvent(highlightrows);
addLoadEvent(displayabbreviations);

</script>

//为不支持placeholder的浏览器添加这个功能
function resetfields(whichform){
  if(Modernizr.input.placeholder) return ;
    for(var i=0; i<whichform.elements.length;i++){
      var element = thichform.elements[i];
        if(element.type == 'submit') continue;
        var check = element.placeholder || element.getAttribute('placeholder');
        if(!check) continue;
        element.onfocus = function(){
          var text = this.placeholder || this.getAttribute('placeholder');
            if(this.value == text){
              this.className = '';
                this.value = '';
            }
        }
        element.onblur = function(){
          if(this.value == ''){
              this.className = 'placeholder';
                this.value = this.placeholder || this.getAttribute('placeholder');
            }
        }
        element.onblur();
    }
}

function prepareforms(){
  for(var i=0; i<document.forms.length; i++){
      var thisform = document.forms[i];
        resetfields(thisform);
    }
}

addLoadEvent(prepareforms);

//表单验证
function isfilled(field){
  if(field.value.replace(' ','').length == 0) return false;
    var placeholder = field.placeholder || field.getAttribute("placeholder");
    return (field.value!=placeholder);
}

function isemail(field){
  return (field.value.indexOf("@") != -1 && field.value.indexOf(".") !=-1);
}

function validateform(whichform){
  for(var i=0; i<whichform.elements.length; i++){
      var element = thichform.elements[i];
        if(element.required == 'required'){
          if(!isfilled(element)){
              alert("Please fill in the "+element.name+" field.");
                return false;
            }
        }
        if(element.type == 'email'){
          if(!isemail(element)){
              alert("the "+element.name+ "field must be a valid email address.");
                return false;
            }
        }
    }
    return false;
}

function prepareforms(){
  for(var i=0; i<document.forms.length; i++){
      var thisform = document.forms[i];
        resetfields(thisform);
        thisform.onsubmit = function(){
          return validateform(this);
        }
    }
}

//ajax
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 submitFormWidthAjax(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;
}

function prepareForms(){
  for(var i=0; i<document.forms.length; i++){
      var thisform = document.forms[i];
        resetFields(thisform);
        thisform.onsubmit = function(){
          if(!validateForm(this)) return false;
            var article = document.getElementsByTagName("article")[0];
            if(submitFormWithAjax(this,article)) return false;
            return true;
        }
    }
}