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$(function(){
    //初始化设置
    var zIndex = 1;
    $('.div1').css('zIndex', zIndex);
    zIndex += 1;
    $('.div2').css('zIndex', zIndex);
    zIndex += 1;
    $('.div3').css('zIndex', zIndex);
    zIndex += 1;
    //窗体点击事件
    $('div').click(function(){
        var thisDOM = $(this);
        var baseStartY = thisDOM.offset().top, baseEndY = baseStartY + thisDOM.height();
        var baseStartX = thisDOM.offset().left, baseEndX = baseStartX + thisDOM.width();
        var baseCenterX = baseStartX + (thisDOM.width() / 2);
        var baseZIndex = parseInt(thisDOM.css('zIndex'));
        $('div:not(.' + thisDOM.attr('class') + ')').each(function(){
            //整理好四角坐标
            var thisStartY = $(this).offset().top, thisEndY = thisStartY + $(this).height();
            var thisStartX = $(this).offset().left, thisEndX = thisStartX + $(this).width();
            var thisCenterX = thisStartX + ($(this).width() / 2);
            var thisZIndex = parseInt($(this).css('zIndex'));
            //依次比较四角坐标
            var flag = false;
            if(thisZIndex > baseZIndex){
                if(thisStartX >= baseStartX && thisStartX <= baseEndX && thisStartY >= baseStartY && thisStartY <= baseEndY){
                    flag = true;
                }else if(thisStartX >= baseStartX && thisStartX <= baseEndX && thisEndY >= baseStartY && thisEndY <= baseEndY){
                    flag = true;
                }else if(thisEndX >= baseStartX && thisEndX <= baseEndX && thisStartY >= baseStartY && thisStartY <= baseEndY){
                    flag = true;
                }else if(thisEndX >= baseStartX && thisEndX <= baseEndX && thisEndY >= baseStartY && thisEndY <= baseEndY){
                    flag = true;
                }
            }
            if(flag){
                if($(this).attr('class') == 'div1'){
                    alert('红色');
                }else if($(this).attr('class') == 'div2'){
                    alert('蓝色');
                }else if($(this).attr('class') == 'div3'){
                    alert('黄色');
                }
            }
        });
        $(this).css('zIndex', zIndex);
        zIndex += 1;
    });
});

<div class="div1"></div>
<div class="div2"></div>
<div class="div3"></div>

div{position:absolute;width:200px;height:100px;background:#fff}
.div1{top:100px;left:270px;background:red}
.div2{top:50px;left:240px;background:blue}
.div3{top:75px;left:300px;background:yellow}