javascript – 未捕获的TypeError：this.state.data.map不是函数

我是React的新手,看过一些类似的问题,但没有发现为什么会这样.我得到一个“未捕获的TypeError：this.state.data.map不是一个函数”.
这是代码.请帮忙找出问题所在.

class Audienses extends React.Component {

    constructor (props)
    {
        super(props);

        this.state = {
            data: ''
        };

        this.loadFromServer = this.loadFromServer.bind(this);
        this.childeDelete = this.childeDelete.bind(this);
        this.childeEdit = this.childeEdit.bind(this);

    }

    loadFromServer () {
        var xhr = new XMLHttpRequest();
        xhr.open('get', this.props.url, true);
        xhr.onload = function() {
            var data = JSON.parse(xhr.responseText);
            this.setState({ data: data });

        }.bind(this);
        xhr.send();
    }

    componentDidMount() {
        this.loadFromServer();   
    }


     render () {

         var audienses = this.state.data.map((value, index) => (
           <OneElement key={value.id} audience={value.audience} description={value.description} />
        ));

        /* or like this
         var audienses = this.state.data.map(function(s) {
             <OneElement key={s.id} audience={s.audience} description={s.description} onDeleteClick={this.childeDelete} oneEditClick={this.childeEdit} />
         }).bind(this);
        */
         return
        <div>
            <h1>Audiences</h1>
            <table id="services">
                <tr>
                    <th>Audience</th>
                    <th>Description</th>
                    <th></th>
                    <th></th>
                </tr>
                <tbody>
                   {audienses}
                </tbody>
            </table>
        </div>;
    }
}

解决方法:

您的初始数据状态是String.,String没有方法.map,您需要将初始状态从”更改为[]

this.state = {  data: [] };

标签：javascript,reactjs,react-jsx
来源： https://codeday.me/bug/20190930/1837009.html