OnChanges

Implement this interface to get notified when any data-bound property of your directive changes.

ngOnChanges is called right after the data-bound properties have been checked and before view and content children are checked if at least one of them has changed.

The changes parameter contains an entry for each changed data-bound property. The key is the property name and the value is an instance of SimpleChange.

Examples

Try this live example from the Lifecycle Hooks page:

ngOnChanges(Map<String, SimpleChange> changes) { changes.forEach((String propName, SimpleChange change) { String cur = JSON.encode(change.currentValue); String prev = change.isFirstChange() ? "{}" : JSON.encode(change.previousValue); changeLog.add('$propName: currentValue = $cur, previousValue = $prev'); }); }