JS：day06

一、两种遍历方式

for循环

    var arr = [1,2,3,4,5]
    for（var i=0;i<arr.length;i++）{
          console.log(arr[i])
  }

for in

    /*for in
    key表示下标值
    * */
    for(key in arr){
        console.log(arr[key])
    }

二、充实文档的内容

1.onload事件（addLoadEvent）

function addLoadEvent(func){
    /*1.把window.onload事件的处理函数存入变量oldonload*/
    /*2.如果window.onload没有绑定任何函数,则给它添加新的函数
     *3.如果在window.onload上已经绑定了函数,就把新函数追加到末尾。
     * */
    var oldonload = window.onload;
    if(typeof oldonload != "function"){
        window.onload = func;
    }else{
        window.onload = function(){
            oldonload();
            func();
        }
    }
}

2.动画 moveElement函数

function moveElement(elemenID,final_x,final_y,interval){
    //移动元素
    if(!document.getElementById)return false;
    if(!document.getElementById(elemenID))return false;
    var elem = document.getElementById(elemenID);
    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);
    var dist = 0;


    if(xpos == final_x && ypos == final_y){
        return true;
    }
    if(xpos < final_x){
        //xpos++;
        dist = Math.ceil((final_x - xpos)/10);
        xpos = xpos + dist;
    }
    if(xpos > final_x){
        //xpos--;
        dist = Math.ceil((xpos - final_x)/10);
        xpos = xpos - dist;
    }
    if(ypos < final_y){
        //ypos++;
        dist = Math.ceil((final_y - ypos)/10);
        ypos = ypos + dist;
    }
    if(ypos > final_y){
        //ypos--;
        dist = Math.ceil((ypos - final_y)/10);
        ypos = ypos - dist;
    }


    elem.style.left = xpos + "px";
    elem.style.top = ypos + "px";
    var repeat = "moveElement('"+elemenID+"',"+final_x+","+final_y+","+interval+")";
    elem.movement = setTimeout(repeat,interval);
}