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<!DOCTYPE html> < html lang = "en" >
< head >
< meta charset = "utf-8" >
< title >CSS-DOM</ title >
< link rel = "stylesheet" type = "text/css" href = "10.css" >
< script src = "10.js" ></ script >
</ head >
< body >
< p id = "message" >
Whee! </ p >
</ body >
</ html >
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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" ,200,100,10);
} function moveElement(elementID,final_x,final_y,interval){
if (!document.getElementById) return false ;
if (!document.getElementById(elementID)) return false ;
var elem = document.getElementById(elementID);
var xpos = parseInt(elem.style.left); //parseInt(string)把字符串里面的数值信息提取出来,因为后面要进行很多算术比较操作。
var ypos = parseInt(elem.style.top); //parseFloat(string)可以把带小数的数值(也就是浮点数)提取出来。
if (xpos == final_x && ypos == final_y){
return true ;
} if (xpos < final_x){ xpos++;} //如果xpos小于终点的left,给它加1.
if (xpos > final_x){ xpos--;} //如果xpos大于终点的left,给它减1.
if (ypos < final_y){ ypos++;} //如果ypos小于终点的left,给它加1.
if (ypos > final_y){ ypos--;} //如果ypos大于终点的left,给它减1.
elem.style.left = xpos + "px" ;
elem.style.top = ypos + "px" ;
//var repeat = function() {moveElement(elementID, final_x,final_y,interval)} var repeat = "moveElement('" + elementID + "'," + final_x + "," + final_y + "," + interval + ")" ;
movement = setTimeout(repeat,interval); //clearTimeout(movement); 在等待的interval那时间内,可以取消这一“跳跃”行为 } addLoadEvent(positionMessage);
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本文转自 小旭依然 51CTO博客,原文链接:http://blog.51cto.com/xuyran/1783911