Example for loading external scripts using jQuery

load-external-script-with-jquery.js

if( typeof jQuery != 'undefined' ) {
    jQuery.getScript( '//cdnjs.cloudflare.com/ajax/libs/history.js/1.8/bundled-uncompressed/html4+html5/jquery.history.js' ).done(function( script, textStatus ) {
        console.info( 'successfully loaded History.js');
        if( typeof History != 'undefined') {
            console.log( 'ready to use History.js')
        }
    }).fail(function( jqxhr, settings, exception ) {
        console.error('failed to load History.js')   
    });
}