ReactJS - this.state. [Objekt] .map ist keine Funktion?

Question

Warum erhalte ich diesen Fehler an einem Live-Server:

Uncaught TypeError: this.state.navitems.map is not a function

Aber ich diesen Fehler nie auf meinem localhost bekommen.

Die reactjs:

import React from 'react'; import $ from 'jquery'; 

import NavItem from './nav-item'; 

class Footer extends React.Component { 
    constructor(props) { 
     super(props); 
     this.state = { 
      navitems: [], 
     }; 
    } 

    // Then fetch the data using $.get(): 
    componentDidMount() { 
     this.serverRequest = $.get(this.props.source, function (result) { 
      this.setState({ 
       navitems: result 
      }); 
     }.bind(this)); 
    } 

    componentWillUnmount() { 
     this.serverRequest.abort(); 
    } 

    render() { 
     var loop = this.state.navitems.map(function(item, index){ 
      return <NavItem key={index} item={item}></NavItem>; 
     }); 

     return (
      <div> 
       <div className="nav"> 
        <ul>{ loop }</ul> 
       </div> 
      </div> 
     ) 
    } } 

export { Footer as default } 

Irgendwelche Ideen, wie ich dieses Problem beheben?

EDIT:

componentDidMount() { 
    console.log('props.source', this.props.source); 
    this.serverRequest = $.get(this.props.source, function (result) { 
     console.log('returned result', result); 
     this.setState({ 
      navitems: result 
     }); 
    }.bind(this)); 
} 

Ergebnis:

props.source ./data/nav.json 

returned result [{ 
    "navId": "1", 
    "title": "Home", 
    "code": "home", 
    "href": null, 
    "style": null, 
    "sort": "1", 
    "url": "#", 
    "parentId": null, 
    "totalChildren": "0", 
    "createdOn": null, 
    "updatedOn": null 
}, { 
    "navId": "2", 
    "title": "About", 
    "code": "about", 
    "href": null, 
    "style": null, 
    "sort": "2", 
    "url": "#", 
    "parentId": null, 
    "totalChildren": "0", 
    "createdOn": null, 
    "updatedOn": null 
}, { 
    "navId": "3", 
    "title": "Contact", 
    "code": "contact", 
    "href": null, 
    "style": null, 
    "sort": "3", 
    "url": "contact", 
    "parentId": null, 
    "totalChildren": "0", 
    "createdOn": null, 
    "updatedOn": null 
}] 

Answer 1

ich Ihr Problem wahrscheinlich erraten würde liegt hier:

// Then fetch the data using $.get(): 
componentDidMount() { 
    this.serverRequest = $.get(this.props.source, function (result) { 
     this.setState({ 
      navitems: result 
     }); 
    }.bind(this)); 
} 

Können Sie inspizieren, was this.props.source gleich? Wenn es korrekt ist, haben Sie Probleme mit Cross-Domain-Anfragen? Fügen Sie in einigen Protokollierung und sehen, was der Inspektor gibt Ihnen:

// Then fetch the data using $.get(): 
componentDidMount() { 
    console.log('props.source', this.props.source); 
    this.serverRequest = $.get(this.props.source, function (result) { 
     console.log('returned result', result); 
     this.setState({ 
      navitems: result 
     }); 
    }.bind(this)); 
} 

Answer 2

Meine schnelle Lösung - $.getJSON:

componentDidMount() { 
     this.serverRequest = $.getJSON(this.props.source, function (result) { 
      this.setState({ 
       article: result 
      }); 
     }.bind(this)); 
    }