限制父组件传递到子组件元素的类型
import PropTypes from 'prop-types';
TodoItem.propTypes = {
test: PropTypes.string.isRequired,
content: PropTypes.arrayOf(PropTypes.number, PropTypes.string),
deleteItem: PropTypes.func,
index: PropTypes.number
}设置默认值
TodoItem.defaultProps = {
test: 'hello world'
}