Error in JQuery core

Error in JQuery core

Hello, I am new to JQuery and I downloaded a JQuery core file. When I loaded it into DreamWeaver it told me there is an error in the code. I am hoping you guys can quickly tell me how to fix it! 

DreamWeaver says that there is a syntax error on the line that says "  .catch(function(error){   "

Any Ideas? Thank you!

jQuery.fn.ready = function( fn ) {

.then( fn )

// Wrap jQuery.readyException in a function so that the lookup
// happens at the time of error handling instead of callback
// registration.
.catch( function( error ) {
jQuery.readyException( error );
} );

return this;