jquery - execute function not more than one time -

i wrote code shown below call lightbox show , callback function, example function_a, fire 16 times.

how can make fire once?

$("#open").click(function(){     $('.a, .b, .c, .d').fadeout(600,function(){         $('.e, .f, .g, .h').fadein(400,function(){             function_a();         });     }); });  function_a(){     console.log('fire') }; 

you can use $.fn.promise, f.ex:

$("#open").click(function(){     $('.a, .b, .c, .d').fadeout(600).promise().done(function(){         $('.e, .f, .g, .h').fadein(400).promise().done(function(){             function_a();         });     }); }); 

from docs:

the .promise() method returns dynamically generated promise resolved once actions of type bound collection, queued or not, have ended.

also note classnames must @ least 2 characters long.