JSFiddle - React, Tailwind, and code Playground

JavaScript

Ext.onReady(function(){
  var _idGen = 1;
  var childItems = [], items = [];

  for (var i = 0; i < 9; i++) {
    childItems.length = 0;
    for (var j = 0; j < 9; j++) {
       childItems.push({
           xtype: 'panel',
 /****************************/
           id: _idGen,
           html: _idGen + "",
 /****************************/
           width: 50,
           height: 50,
           style: {margin: '1px',borderColor: 'white',backgroundColor:'cornflowerblue'}
       });
       console.log(_idGen);
/*****************************/
      _idGen++;
/*****************************/
    }
    items.push({
        xtype: 'panel',
        layout: {
            type: 'table',
            columns: 3
        },

        items: childItems
    });
  }
  Ext.create('Ext.container.Container', {
     layout: {
        type: 'table',
        // The total column count must be specified here
        columns: 3
     },
     renderTo: Ext.getBody(),    
     style: {width: '455px',marginLeft: 'auto',marginRight: 'auto', marginTop: '30px'},
     items: items
  });

});