What purpose does the following code serve? What does factory function do here? Here root is window object. Is factory a default java script function? In what kind of scenarios this type of code can be used. This code is from toggle.js from Simon Tabor. Zepto and ender are libraries. Is this mostly used in libraries.
if (typeof define === 'function' && define['amd']) {
define(['jquery'], factory);
} else {
factory(root['jQuery'] || root['Zepto'] || root['ender'] || root['$']|| $);
}