Cannot use TextEditor Option

I’m developing an app using vue.js and go.js.

So far so good.
But now I need a dropdown box on my panel.
I follow this example Text Editing Examples

And here is my snippet code

var myScenarioDiagram =
                    $(go.Diagram, this.$el, 
                        mouseDrop: this.onDroppedBox
                        "toolManager.mouseWheelBehavior": go.ToolManager.WheelZoom,
                        allowDrop: true, 
                        initialAutoScale: go.Diagram.Uniform,
                        "textEditingTool.defaultTextEditor": window.TextEditorSelectBox, 
                        "undoManager.isEnabled": true,
                            { direction: 90, layerSpacing: 6, columnSpacing: 6, setsPortSpots: false })

But I got this error when ever it reached “textEditingTool.defaultTextEditor”: window.TextEditorSelectBox,

go.js?3c55:666 Uncaught TypeError: Cannot read property ‘style’ of undefined
at hk.doActivate (go.js?3c55:666)
at ih.doMouseUp (go.js?3c55:685)
at D.doMouseUp (go.js?3c55:757)
at HTMLCanvasElement.El.a.Pn (go.js?3c55:967)

Is there any mistake or mis-doing I made ?

What is the value of customSelectBox when you get the error?

It is “undefined”.

Is there any pre-step I had to take first?

Have you loaded the script tag at the top of the file?

<script src="../extensions/TextEditorSelectBox.js"></script>

I think that’s the problem, I made a mistake.

Other .js library in my vue,js are not needed to be imported, so I think the same to TextEditorSelectBox.js extension.
But after importing it, it is working now.

Thank you !