When we are creating plugins or simple code in jQuery and there is a single or many plugin dependences among them, a common task is to implement a mechanism to validate if a jQuery plugin exists before running “depending” code, for example if we have this code and we have not included jqprint (a nice plugin to print a fragment of an HTML document), then an error will appear indicating that jqprint function is undefined.
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(function($) { $(document).ready(function() { $(".print-this-section").on('click', function(){ $("#section-to-print").jqprint(); }); }); })(jQuery); |
So, in order to solve this “undefined” error we could add a little validation before running jqprint code.
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(function($) { $(document).ready(function() { if( jQuery().jqprint ){ // Verifying jqprint exists $(".print-this-section").on('click', function(){ $("#section-to-print").jqprint(); }); } }); })(jQuery); |
With this simple code, you would be able to avoid errors in your code when a plugin is not defined.
That’s it!
Be happy with your code!
—
Alex Arriaga 
