addSizes.js 是一段JS代码,用于从一个页面里链接的一些大的文件,并自动在它们的链接旁边标注文件大小。它的作者是 Nathalie Downe，应用了Simon Willison 的 json-head App Engine迷你服务。

使用它，你的链接不需要额外的代码，它自动会在页面里找到你的链接并更改为这样的格式，如”你的链接(pdf 2.8 MB)”。的确很好用！

JAVASCRIPT.:

jQuery(function($){

    $('a[href$=".pdf"], a[href$=".doc"], a[href$=".mp3"], a[href$=".m4u"]').each(function(){

         // looking at the href of the link, if it contains .pdf or .doc or .mp3

         var link = $(this);

         var bits = this.href.split('.');

         var type = bits[bits.length -1];

         var url= "http://json-head.appspot.com/?url="+encodeURI($(this).attr('href'))+"&callback=?";

         // then call the json thing and insert the size back into the link text

         $.getJSON(url, function(json){

                if(json.ok && json.headers['Content-Length']) {

                        var length = parseInt(json.headers['Content-Length'], 10);

                        // divide the length into its largest unit

                        var units = [

                              [1024 * 1024 * 1024, 'GB'],

                              [1024 * 1024, 'MB'],

                              [1024, 'KB'],

                              [1, 'bytes']

                         ];

                         for(var i = 0; i {

                               var unitSize = units[i][0];

                               var unitText = units[i][1];

                               if (length>= unitSize) {

                                       length = length / unitSize;

                                       // 1 decimal place

                                       length = Math.ceil(length * 10) / 10;

                                       var lengthUnits = unitText;

                                        break;

                               }

                         }

                         // insert the text directly after the link and add a class to the link

                         link.after(' (' + type + ' ' + length + ' ' + lengthUnits + ')');

                         link.addClass(type);

                    }

           });

     });