FormArray insert and setControl insert items on wrong index

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[ ] feature request
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Current behavior Documentation for insert says that item is inserted on the given index.

Insert a new AbstractControl at the given index in the array.

However if the controls collection is empty the item is always inserted on first position. The issue is due to inappropriate usage of splice here.

Expected behavior To always insert the item at the given index.

Minimal reproduction of the problem with instructions http://plnkr.co/edit/zS5RlQhRVWpviWWK99JO?p=preview

What is the motivation / use case for changing the behavior? We need to add FormGroups dynamically in FormArray based on relative index and later retrieve it back from that index.

• Angular version: 2.2.3

[rusev]

@kara Please re-open this issue! insert documentation claims that items is inserted at position. I’m not willing to use setControl. setControl will not work if there isn’t item at the given position, while insert should work. What is the purpose of the index parameter then? It is pointless unless the array is already populated.

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