ExtJs simplest possible DI ( Dependency Injection )

extjs-di.js

Ext.application({
    name : 'Fiddle',

    launch : function() {
        var a = DependencyInjector.provide('A');
        Ext.Msg.alert('Fiddle', a.getString());
    }
});

Ext.define('DependencyContainer', {
    singleton: true,
    deps: {
        A: {
            prop: 'C'
        },
        C: {
            oldValObj: 'B'
        }
    }
})

Ext.define('DependencyInjector', {
    singleton: true,
    provide: function(className) {
    	var clazz = DependencyContainer.deps[className];
        var depsConfig = {};
        
        if (clazz) {
            var keys = Object.keys(clazz);
            keys.forEach(function(key) {
                depsConfig[key] = this.provide(clazz[key])
            }, this);
        }
    	
        var obj = Ext.create(className)
        return Ext.apply(obj, depsConfig);
	}
});

Ext.define('A', {
    getString: function() {
        return this.prop.getValue();
    }
})
    
Ext.define('B', {
    getValue: function() {
        return 'Welcome to Sencha Fiddle!'
    }
})

Ext.define('C', {
    getValue: function() {
        return this.oldValObj.getValue() + ' TTT!!!';
    }
})