offsetTop :当前对象到其上级层顶部的距离.
offsetLeft :当前对象到其上级层左边的距离.
比如：
父div的四个点的位置是(0,0),(0,width1),(height1,0),(height1,width1)
而子div的四个点的位置是(offsetTop,offsetLeft),(offsetTop ,offsetLeft+width2),(offsetTop+height2,offsetLeft),(offsetTop+height2,offsetLeft+width2)
然后对比这些点的位置即可
reatejs，看看你应该能懂1
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//敌机与子弹的碰撞检测
function updateEnemy(){
var i, j,fire,enemy1
for(i=0i<fires.lengthi++){
for(j=0j<enemy.lengthj++){
fire = fires[i]
enemy1 = enemy[j]
var fx = fire.x
var fy = fire.y
var ex = enemy1.x
var ey = enemy1.y
var ew = enemy1.getBounds().width
var eh = enemy1.getBounds().height
if(ey>=800 || ex>=600){
enemy.splice(j,1)
stage.removeChild(enemy1)
}
if(fy <ey+eh &&fy >ey &&fx>ex &&fx<ex+ew &&ey >0){
score += 10
fires.splice(i,1)
enemy.splice(j,1)
stage.removeChild(fire)
stage.removeChild(enemy1)
createjs.Sound.play("explosion")
var exp1 = new createjs.Sprite(spriteSheet,"exp")
exp1.x = ex
exp1.y = ey
exp1.addEventListener('animationend',function(e){
stage.removeChild(e.target)
})
stage.addChild(exp1)
}
}
