react post传递数据有问题

代码如下:

var CommentBox = React.createClass({
    loadCommentsFromServer: function(){
        $.ajax({
            url: this.props.url,
            dataType: 'json',
            success: function(data){
                this.setState({data: data});
            }.bind(this),
            error: function(xhr,status,err){
                console.log(this.props.url,status,err.toString());
            }.bind(this)
        });    
    },  

    handleCommentSubmit: function(comment){
        var comments = this.state.data;
        var newComments = comments.concat([comment]);
        this.setState({data: newComments});
        $.ajax({
            url: this.props.url,
            dataType: 'json',
            type: 'POST',
            data: comment,
            success: function(data){
                this.setState({data: data});
            }.bind(this),
            error: function(xhr,status,err){
                console.error(this.props.url,status,err.toString());
            }.bind(this)
        });
    },  
    getInitialState: function(){
        return {data: []};
    },  

GET方法获取数据没有问题，但POST方法提交数据总是报comments.json not found 404错误。