POC imagemagick for resize and change name of images

imagemagick.js

var S = require('string');
var moment = require('moment');
var util = require('util');
var im = require('node-imagemagick');
var _ = require("underscore");

var sizes = [{
    width: 200,
    name: '-small'
}, {
    width: 300,
    name: '-thumb'
}, {
    width: 780,
    name: '-post'
}];

//var fileSrc = 'game_original.jpg';
var fileSrc = 'alyson_original.gif';
//var fileSrc = 'beyonce_original.gif';
//var fileSrc = 'lookbook_original.jpg';

_.each(sizes, function(ele) {

    im.identify(fileSrc, function(err, output) {
        if (err) throw err;

        console.log('width : ' + output.width);

        if ((/(.*?)(\.\w{3,4})$/).test(fileSrc)) {
            var gr = fileSrc.match(/(.*?)(\.\w{3,4})$/);
            //var fileDst = gr[1] + ele.name + gr[2];
            var fileDst = gr[1] + ele.name + '.jpg';

            if (output.width <= 780 && ele.width == 780)
                ele.width = output.width;

            if (S(gr[2]).contains('gif')) {
                im.convert([fileSrc+'[1]', '-resize', ele.width+'x', fileDst], function(err, stdout) {
                        if (err) throw err;
                    });

            } else {
                im.resize({
                    srcPath: fileSrc,
                    dstPath: fileDst,
                    width: ele.width,
                    quality: 0.6
                }, function(err, stdout, stderr) {
                    if (err) throw err;
                });
            }
        }

    });

});