$("input").trigger("click");
$( "#foo" ).on( "click", function() {
alert( $( this ).text() );
});
$( "#foo" ).trigger( "click" );
$( "#foo" ).on( "custom", function( event, param1, param2 ) {
alert( param1 + "\n" + param2 );
});
$( "#foo").trigger( "custom", [ "Custom", "Event" ] );
$('#textareaID').bind('input propertychange', function() {
$("#yourBtnID").hide();
if(this.value.length){
$("#yourBtnID").show();
}
});