Kendo combobox auto select

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Javascript

Kendo-UI

Hello, I have some codes written in Javascript as follow.
The purpose is to auto select the combobox first value when it has only one(1) value.
I tested my codes in Kendo Dojo and it worked. But not when I run the codes at my local PC using debug mode.

var arr = [];
arr.push('JMT');

$('#cmbTesting').kendoComboBox({
   placeholder: "Select",
   dataSource: arr,
   dataBound: function (e) {
     if (e.sender.items().length == 1) {
        this.select(0);
     }
   },
});

What I have tried:

1. Tried remove placeholder but not the root cause here.
2. Ctrl+F5 to refresh not not working as well.
3. Explicitly hardcoded the dataSource: ['JMT'] but not working as well.