# 4.1 UDI.onContextChange()

UDI.onContextChange() is called whenever there is a change to the chart such as a switch of market or timeframe. The function receives a data parameter which contains the same context information which is passed to UDI.onInit(). 

For example:

```
UDI.onContextChange = function(data) 
{
	// Get current chart timeframe
	var tf = data.context.instrument.timeframe;
};
```


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