dat.gui/elements/controller-string/controller-string.js

Gui.register( 'controller-string', function( value ) {
  
    return typeof value == 'string';

} );

Polymer( 'controller-string', {

    click: function( e ) {

        this.$.input.select();

    },

    keydown: function( e ) {

        if ( e.keyCode == 13 ) {
            this.$.input.blur();
        }

    }
    
});