问子组件的props内部返回零的数组长度

EN

 {this.state.items.length}
                <Pagination
                    itemsLength={this.state.items.length}
                    currentPage={0}
                    pageCount={2}
                />

import React, { Component } from 'react';

class Pagination extends Component {

    pageArray = [];

    componentDidMount = () => {
        console.log(this.props.itemsLength);
        let { itemsLength, currentPage, pageCount } = this.props;
        let pages = Math.ceil(itemsLength / pageCount);

        console.log('itesm length ', itemsLength);


        for (let i = 0; i < pages; i++) {
            this.pageArray.push(i + 1);
        }

        console.log('page array ', this.pageArray);
    }
    render() {
        return (
            <div>
                {
                    this.pageArray.map(
                        page => {
                            return (<button>page</button>);
                        }
                    )
                }
            </div>
        );
    }
}

export default Pagination;