画任意两点之间的连线

function drawLine(obj1, obj2){

var oneTop = $(obj1).position().top;

var oneLeft = $(obj1).position().left;

var twoTop = $(obj2).position().top;

var twoLeft = $(obj2).position().left;

var chaWidth = Math.abs(oneLeft-twoLeft);

var chaHeight = Math.abs(oneTop-twoTop);

var line = Math.pow(chaWidth,2)+Math.pow(chaHeight,2);

var lineLength = Math.sqrt(line);

var angle = Math.atan2(chaHeight, chaWidth)/2/Math.PI*360;

var lineDiv = $("<div></div>");

$(lineDiv).width("2px");

$(lineDiv).css({

"backgroundColor": "red",

"position": "absolute"

});

$(lineDiv).css({

"left": oneLeft,

"top": oneTop,

"-webkit-transform-origin": "top",

"-webkit-transform": "rotate(" + (-angle) + "deg)"

});

console.log($(lineDiv).css("left"));

$("body").append(lineDiv);

var timer = setInterval(function(){

i++;

$(lineDiv).height(i);

if ($(lineDiv).height() >= lineLength) {

$(lineDiv).height(lineLength);

clearInterval(timer);

}

},10);

}