each的使用

js查找多个元素后对每一个元素进行操作

            $( ".img").find("img" ).each(function (index, eleDom) {

                var imgwidth = $( this).width();

                var align;

                if (imgwidth > 800) {

                    align = "6px";

                    $( this).css({ "width": "800px" , "height" : "auto" });

                } else {

                    align = (812 - imgwidth) / 2;

                }

                var w = (align + "px");

                $( this).css({

                    "margin-left": w,

                    "margin-right": "auto"

                });});