Question

实际上，我一直试图添加一个删除评论＆＃39;我的评论框系统的功能。

这是我的代码： -

var Comment = React.createClass({
  handleClick: function(e){
    e.preventDefault();
    var commentId = this.props.comment.id;
    return this.props.onDelete(commentId);
  },
  render: function () {
    return (
      <div className="comment">
        <h4 className="commentAuthor">
          {this.props.comment.email}
        </h4>
          {this.props.comment.comment}
          <a onClick={this.handleClick}> &times; </a>
      </div>
      );
  }
});

var CommentList = React.createClass({
  handleDelete: function(commentId){
    return this.props.del(commentId);
  },
  render: function () {
    var commentNodes = this.props.comments.map(function (comment, index) {
      return (
        <Comment comment = {comment} onDelete = {this.handleDelete} key = {index} />
        );
    });

    return (
      <div className="commentList">
        {commentNodes}
      </div>
      );
  }
});

var CommentBox = React.createClass({
  getInitialState: function () {
    return {comments: []};
  },
  componentDidMount: function () {
    this.loadCommentsFromServer();
  },
  loadCommentsFromServer: function () {
    $.ajax({
      url: this.props.url,
      dataType: 'json',
      success: function (comments) {
        this.setState({comments: comments});
      }.bind(this),
      error: function (xhr, status, err) {
        console.error(this.props.url, status, err.toString());
      }.bind(this)
    });
  },
  handleCommentSubmit: function(comment) {
    var comments = this.state.comments;
    var newComments = comments.concat([comment]);
    this.setState({comments: newComments});
    $.ajax({
      url: this.props.url,
      dataType: 'json',
      type: 'POST',
      data: {"comment": comment},
      success: function(data) {
        this.loadCommentsFromServer();
      }.bind(this),
      error: function(xhr, status, err) {
        console.error(this.props.url, status, err.toString());
      }.bind(this)
    });
  },
  delc: function(commentId){
    $.ajax({
      url: this.props.url,
      data: {"id" : commentId},
      type: 'DELETE',
      dataType: 'json',
      success: function (comments) {
        this.setState({comments: comments});
      }.bind(this), 
      error: function(xhr, status, err) {
        console.error(this.props.url, status, err.toString());
      }.bind(this)
      });
  },
  render: function () {
    return (
      <div className="commentBox">
        <h1>Comments</h1>
        <CommentList del={this.delc} comments={this.state.comments} />
        <CommentForm onCommentSubmit={this.handleCommentSubmit}/>
      </div>
      );
  }
});

var CommentForm = React.createClass({
  handleSubmit: function() {
    var email = this.refs.email.getDOMNode().value.trim();
    var comment = this.refs.comment.getDOMNode().value.trim();
    this.props.onCommentSubmit({email: email, comment: comment});
    this.refs.email.getDOMNode().value = '';
    this.refs.comment.getDOMNode().value = '';
    return false;
  },

  render: function() {
    return (
      <form className="commentForm" onSubmit={this.handleSubmit}>
        <input type="email" placeholder="Your email" ref="email" />
        <input type="text" placeholder="Say something..." ref="comment" />
        <input type="submit" value="Post" />
      </form>
      );
  }
});

var ready = function () {
  React.renderComponent(
    <CommentBox url="18/comments.json" />,
    document.getElementById('art')
  );
};

$(document).ready(ready);

现在，当我尝试删除评论时，会抛出一条错误，上面写着“未捕获的TypeError：undefined不是函数”

切换到＆＃39;来源＆＃39; devTool上的标签，我发现问题出在＆＃39; onDelete＆＃39;功能

它说，＆＃39; onDelete＆＃39;功能未定义。

我认为这个问题是由于这个＆＃39;关键字，但我不确定。

我该怎么做才能解决这个问题？如果我错过了什么，请告诉我。（我是新手）

提前谢谢。

Answer 1

传递给map的函数不会自动与您的反应类共享this指针。

要在匿名函数中使用this，请在函数定义的末尾调用.bind(this)以生成一个内部具有预期this的函数。

var commentNodes = this.props.comments.map(function (comment, index) {
    ...
});

变为：

var commentNodes = this.props.comments.map(function (comment, index) {
    ...
}.bind(this));

删除评论 - React js

1 个答案: