$(function(){
  masonryInit(".grid-container", ".grid-item")
})

function masonryInit(containerClass, itemClass){
  //class需要有帶點 如 ".class"
  var  _grid = $(containerClass).imagesLoaded(function(){
      _grid.masonry({
          itemSelector: itemClass,
          gutter: '.gutter-sizer',
      });
  });
}