[nickpresta]

I'm very excited about:

    React.Children.map now returns plain arrays too

Before this change, we would have to do the following when checking the types of children components (in propType validation):

    const childrenTypes = [];
    React.Children.forEach(props.children, child => {
      childrenTypes.push(child.type);
    });
    for (const type of childrenTypes) {
      if (type !== MyComponent) {
        return new Error(`Child '${type}' is not an instance MyComponent. Check render method of 'ParentComponent'.`);
      }
    }

It sort of made sense that map() on an opaque data structure would return the same type of data structure but in practice this was rarely useful.

Thanks, React team!

[seivan]

This also helps with Typescript that required

  var products:Array<Product> = []
    for (var x in this.props.products) {
      products.push(this.props.products[x])
    }