Learning jQuery 3 - Fifth Edition

Default parameter values

As the number of parameters for a method grows, it becomes less likely that we will always want to specify each one. A sensible set of default values can make a plugin interface much more usable. Fortunately, using an object to pass in our parameters helps with this task; it is simple to omit any item from the object and replace it with a default:

(($) => {  $.fn.shadow = function(opts) {    const defaults = {      copies: 5,      opacity: 0.1    };    const options = $.extend({}, defaults, opts);     // ...   }; })(jQuery); 

Listing 8.13

Here, we have defined a new object called defaults. The utility function $.extend() lets us take the opts object provided as an argument and use it to create a new options object using defaults where necessary. ...