react.dev/cookbook/07-children-prop-type.md

id	title	layout	permalink	prev	next
children-prop-type	Type of the children prop	cookbook	children-prop-type.html	style-prop-value-px.html	controlled-input-null-value.html

Problem

You get errors while manipulating this.props.children inside a component.

Solution

Usually, children is an array of components. To save an extra array allocation, it returns the component itself when there's only one.

This means accessing, for example, this.props.children.length might be misleading, as it could either be the length property of the array of children, or that of a single string component.