<style>
  /*全屏顯示大圖*/
  .opacityBottom{
    width: 100%;
    height: 100%;
    position: fixed;
    background:rgba(0,0,0,0.8);
    z-index:1000;
    top: 0;
    left: 0
  }
  .none-scroll{
    overflow: hidden;
    height: 80%;
  }
  .bigImg{
    width:80%;
    height: 80%;
    left:10%;
    top:10%;
    position:fixed;
    z-index: 10001;
  }
</style>

$(".image_click").click(function () {
  var imgsrc = $(this).attr("src");
  var opacityBottom = '<div id="opacityBottom" style="display: none"><img class="bigImg" src="'+ imgsrc +'" ></div>';
  $(document.body).append(opacityBottom);
  toBigImg();//變大函數(shù)
});
function toBigImg(){
  $("#opacityBottom").addClass("opacityBottom");
  $("#opacityBottom").show();
  $("html,body").addClass("none-scroll");//下層不可滑動
  $(".bigImg").addClass("bigImg");
  /*隱藏*/
  $("#opacityBottom").bind("click",clickToSmallImg);
  $(".bigImg").bind("click",clickToSmallImg);
  var imgHeight = $(".bigImg").prop("height");
  if(imgHeight < h){
    $(".bigImg").css({"top":(h-imgHeight)/2 + 'px'});
  }else{
    $(".bigImg").css({"top":'0px'});
  }
  function clickToSmallImg() {
    $("html,body").removeClass("none-scroll");
    $("#opacityBottom").remove();
  }
};