javascript实现的白板效果(可以直接在网页上写字)_javascript技巧

function draw(){
ball = document.createElement("span");
ball.style.position = "absolute";
ball.style.color = "#FF0000";
ball.style.zIndex = 999999999;
ball.innerHTML = "●";
document.body.appendChild(ball);

ball.style["left"] = mouseX+ "px";
ball.style["top"] = mouseY+ "px";
}
function MousePos(e)
{
e = e || window.event;
var x,y;
if(!document.all){
x = e.pageX;
y = e.pageY;
}
else{
x = event.clientX + document.documentElement.scrollLeft;
y = event.clientY + document.documentElement.scrollTop;
}
return {x:x,y:y};
}
function setXY(e)
{
e = e || window.event;
var pos = MousePos(e);
mouseX = pos.x;
mouseY = pos.y;
draw();
}
window.onload = function(){
document.documentElement.onmousemove = function(e){
e = e || window.event;
setXY(e);
};
}


效果演示代码:
var ball; var mouseX = 100; var mouseY = 100; var angle = 0; var radius = 0; function draw(){ ball = document.createElement("span"); ball.style.position = "absolute"; ball.style.color = "#FF0000"; ball.style.zIndex = 999999999; ball.innerHTML = "●"; document.body.appendChild(ball); ball.style["left"] = mouseX+ "px"; ball.style["top"] = mouseY+ "px"; } function MousePos(e) { e = e || window.event; var x,y; if(!document.all){ x = e.pageX; y = e.pageY; } else{ x = event.clientX + document.documentElement.scrollLeft; y = event.clientY + document.documentElement.scrollTop; } return {x:x,y:y}; } function setXY(e) { e = e || window.event; var pos = MousePos(e); mouseX = pos.x; mouseY = pos.y; draw(); } window.onload = function(){ document.documentElement.onmousemove = function(e){ e = e || window.event; setXY(e); }; } </ script>
[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]
出处：http://www.cnblogs.com/airy