![]() This is why we tend to use database IDs instead. React will be confused because it already had a key called 0 and the reconciliation process will not work correctly. If the first item in the array was removed, then what used to be at index 1 is now at index 0. You can now either return a top level array, or use . This old favorite is appearing Each child in an array or iterator should have a unique 'key' prop. Imagine if we used indexes and our array had 3 items then one was removed.Note also that we're relying on the JavaScript engine preserving object enumeration order here, which is not guaranteed by the spec but is implemented by all major browsers and VMs for objects with non-numeric keys. In React 16 you will be able to return an array from render. The return value of createFragment should be treated as an opaque object you can use the React.Children helpers to loop through a fragment but should not access it directly. What can we do about this So, one solution is to wrap it in a 'div' element. With this change, the two sets of children will be properly reordered in the DOM without unmounting. So we could write the Columns component as follows. We can make use of fragments with syntax.![]() So basically we use React.Fragment where we would normally use a wrapper div. ![]() using array notation has has some confusing differences from normal jsx. The keys of the passed object (that is, left and right) are used as keys for the entire set of children, and the order of the object's keys is used to determine the order of the rendered children. React fragments let you group a list of children without adding extra nodes to the DOM because fragments are not rendered to the DOM. Solved-React: vs array-Reactjs.Var createFragment = require ( 'react-addons-create-fragment' ) if ( this. Using the Fragment component, we can now accomplish the same without the array syntax and without using keys.
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