Javascript实现Jq功能

// 手写JQ

//兼容的通过类名获取信息
function getClass(selector, obj) {
  obj = obj || document
  if (obj.getElementsByClassName) {
    return obj.getElementsByClassName(selector);
  } else {//ie6-8进行处理
    var all = obj.getElementsByTagName('*')
    var arr = []
    for (var i = 0; i < all.length; i++) {
      if (check(all[i].className, selector)) {
        arr.push(all[i])
      }
    };
    return arr;
  }
}
function check(longstr, str) {
  var arr = longstr.split(" ")
  for (var i = 0; i < arr.length; i++) {
    if (arr[i] == str) {
      return true
    }
  };
  return false
}
//兼容的获取或者设置对象的文本信息
function getText(obj, value) {
  if (arguments.length == 1) {
    if (obj.textContent != undefined) {
      return obj.textContent;
    } else {
      return obj.innerText;
    }
  } else if (arguments.length == 2) {
    if (obj.textContent != undefined) {
      obj.textContent = value;
    } else {
      obj.innerText = value;
    };
  }
}
//获取元素的函数
//.one #id div
function $(selector, obj) {
  if (typeof selector == "string") {
    obj = obj || document;
    if (selector.charAt(0) == ".") {
      return getClass(selector.slice(1), obj)
    } else if (selector.charAt(0) == "#") {
      return obj.getElementById(selector.slice(1))
    } else {
      return obj.getElementsByTagName(selector)
    }
  } else if (typeof selector == "function") {
    addEvent(window, "load", selector)
    // window.onload=function(){
    // selector()
    // }
  }
}
//获取一个元素所有的元素子节点
function getChildren(obj) {
  var arr = obj.childNodes;
  var newarr = [];
  for (var i = 0; i < arr.length; i++) {
    if (arr[i].nodeType == 1) {
      newarr.push(arr[i])
    }
  };
  return newarr;
}


function getFist(obj) {
  return getChildren(obj)[0]
}

function getLast(obj) {
  var arr = getChildren(obj)
  return arr[arr.length - 1]
}
function getNext(obj) {
  if (obj.getElementsByClassName) {
    return obj.nextElementSibling
  } else {
    var next = obj.nextSibling;
    if (next == null) {
      return null;
    }
    while (next.nodeType != 1) {
      next = next.nextSibling;
      if (next == null) {
        return null;
      }
    }
    return next;
  }
}
//去上一个兄弟元素
function getPrevious(obj) {
  if (obj.getElementsByClassName) {
    return obj.previousElementSibling
  } else {
    var previous = obj.previousSibling;
    if (previous == null) {
      return null;
    }
    while (previous.nodeType != 1) {
      previous = previous.previousSibling;
      if (previous == null) {
        return null;
      }
    }
    return previous;
  }
}
//兼容的获取元素的样式
function getStyle(obj, attr) {
  if (!obj.currentStyle) {
    return getComputedStyle(obj, null)[attr]
  } else {
    return obj.currentStyle[attr]
  }
}
//插入到某个对象后面
function insertAfter(newobj, obj) {
  var parent = obj.parentNode;
  var next = getNext(obj)
  if (next == null) {
    parent.appendChild(newobj)
  } else {
    parent.insertBefore(newobj, next)
  }
}

// 获取浏览器的高宽
function offsetWindow() {
  var x = document.documentElement.clientWidth;
  var y = document.documentElement.clientHeight;
  return { width: x, height: y }

}

//一个元素有父元素时要计算与顶层距离 而且判断有几个父

function getPosition(obj) {
  var parent = obj.parentNode;
  var left = obj.offsetLeft;
  var top = obj.offsetTop;
  //while判断父元素
  while (parent.nodeName != "BODY") {
    //判断定位属性
    if (getStyle(parent, "position") == "absolute" || getStyle(parent, "position") == "relative") {
      left += (parent.offsetLeft + parseInt(
        getStyle(parent, "borderLeftWidth")
      ))
      top += (parent.offsetTop + parseInt(
        getStyle(parent, "borderTopWidth")
      ))
    }
    parent = parent.parentNode;
  }
  return { x: left, y: top };
}



// 兼容的事件绑定
// obj事件源 envent事件 callback事件处理程序
function addEvent(obj, event, callback) {
  if (obj.addEventListener) {
    obj.addEventListener(event, callback, false)
  } else {
    obj.attachEvent("on" + event, callback)
  }
}


function removeEvent(obj, event, callback) {
  if (obj.removeEventListener) {
    obj.removeEventListener(event, callback, false)
  } else {
    obj.detachEvent("on" + event, callback)
  }
}

// 兼容的添加滚轮事件并且可以区分上下
function mousewheel(obj, upfun, downfun) {
  if (obj.addEventListener) {
    obj.addEventListener("mousewheel", fun, false)
    obj.addEventListener("DOMMouseScroll", fun, false)
  } else {
    obj.attachEvent("onmousewheel", fun)
  }
  // fun 真正的处理程序
  function fun(e) {
    var ev = e || window.event;
    if (ev.detail == -3 || ev.wheelDelta == 120) {
      // 如果upfun存在就执行
      if (upfun) {
        // call 函数调用的时候传递一个参数
        // 这个蚕食将作为函数中的this使用
        upfun.call(obj, e)
      }
    } else if (ev.detail == 3 || ev.wheelDelta == -120) {
      if (downfun) {
        downfun.call(obj, e)
      }
    }
  }
}