Replacement is not working for sometime

javascript
api
gadgets
ooui

#1
/*
	This tool will help you for small edits
	@Use Just select the text and press Shift + E
*/

// Load modules
mw.loader.using(  'oojs-ui-windows', 'oojs-ui-widgets', 'oojs-ui-core', 'oojs-ui', 'oojs', 'mediawiki.notify' ).then( function () {
    $(this).on('keypress', function(event) {

		// Trigger for Shift + E
        if (event.which == 69 && event.shiftKey) {

			// Take Selected Text
            var SelectedText = window.getSelection().toString();
            var pageName = mw.config.get('wgPageName');
            var Api = new mw.Api();
            var wpEditToken = mw.user.tokens.get( 'editToken' );

            function QuickEditor( config ) {
                QuickEditor.super.call( this, config );
            }
            OO.inheritClass( QuickEditor, OO.ui.ProcessDialog );

            QuickEditor.static.name = 'quickEditor';
            QuickEditor.static.title = 'Quick Editor';
            QuickEditor.static.actions = [
                { action: 'submit', label: 'Submit', flags: 'primary' },
                { label: 'Cancel', flags: 'safe' }
            ];

            QuickEditor.prototype.initialize = function () {
                QuickEditor.super.prototype.initialize.apply( this, arguments );
            
                this.panel = new OO.ui.PanelLayout( { padded: true, expanded: false } );
                this.content = new OO.ui.FieldsetLayout();
              
                this.TextAera = new OO.ui.MultilineTextInputWidget( { rows: 20, value: SelectedText } );
                
                this.field = new OO.ui.FieldLayout( this.TextAera, { align: 'top' } );
              
                this.content.addItems( [ this.field ] );
                this.panel.$element.append( this.content.$element );
                this.$body.append( this.panel.$element );

            };

            QuickEditor.prototype.getActionProcess = function ( action ) {
                var dialog = this;
                
                // Trigger Submit button Action
                if ( action === 'submit' ) {
                     textAeraText = this.TextAera.value;
                     Api.get({
                            action: 'parse',
                            page: pageName,
                            prop: 'wikitext',
                            format: 'json'
                    }).done( function (obj) {
                        var QuickEditorwikitext = obj.parse.wikitext['*'];
                        var QuickEditorResult = QuickEditorwikitext.replace( SelectedText, textAeraText )

                        Api.post({
                            action: 'edit',
                            title: pageName,
                            token: wpEditToken,
                            summary: 'QuickEditor (Testing)',
                            text: QuickEditorResult
                        }, {
                            success: function () {
                                // Notify the User
                                mw.notify("You have successful made a edit.", { type: 'info' });
                                setTimeout(function(){ window.location.reload() }, 1500);
                            }
                        });	
                        
                    });

                     return new OO.ui.Process( function () {
                          dialog.close( { action: action } );
                     } );
                }
                return QuickEditor.super.prototype.getActionProcess.call( this, action );
            };

            QuickEditor.prototype.getBodyHeight = function () {
                return this.content.$element.outerHeight( true );
            };
            
            var windowManager = new OO.ui.WindowManager();
            $( 'body' ).append( windowManager.$element );

            var quickEditor = new QuickEditor({
                size: 'medium'
            });
            

            windowManager.addWindows( [ quickEditor ] );
            windowManager.openWindow( quickEditor );
        }
    });

} );

I am working on New Gadget. When I replace small changes then replacement has happened. See https://meta.wikimedia.org/w/index.php?title=User%3AJayprakash12345%2Fsandbox&type=revision&diff=18477902&oldid=18477867

But when I select line and want to replace with new characters then replacement is not happening. What am I doing wrong?