how to remove an item from a list with a click event in ReactJS?

Props on components are immutable, meaning you cannot modify them directly. In your above example if the FilterList component wants to remove an item, it would need to call a callback from the parent component.

A simplified example of this.

FilterApp passes a remove function to FilterList that is called on the onClick event. This will remove an item from the parent, update the state, then cause FilterList to re-render with the new content.

Hope this helps.

Something like the below should work. Let your root component manage state.

var FilterList = React.createClass({
  render: function() {
    var createItem = function(item) {
      return (
        <li>
          <span>{item}</span>
          <a href data-id="{item.id}" class="remove-filter" onClick={this.props.remove.bind(item)}>remove</a>
        </li>

      );
    };
    return <ul>{this.props.items.map(createItem.bind(this))}</ul>;
  }
});

var FilterApp = React.createClass({
  getInitialState: function() {
    return {items: [], item: {
      id: 0,
      type: null
    }};
  },
  onChangeType: function(e){
    this.setState({
      item: {
        id: this.state.items[this.state.items.length],
        type: e.target.value
      }
    });
  },
  remove: function(item, ev){
    ev.preventDefault();

    var items = this.state.items.filter(function(itm){
      return item.id !== itm.id;
    });

    this.setState({ items: items });
  },
  handleSubmit: function(e) {
    e.preventDefault();
    var nextItems = this.state.items.concat([this.state.item]);
    var item = {};
    this.setState({items: nextItems, item: {}});
  },
  render: function() {
    return (
      <div>
        <h3>Filters</h3>
        <FilterList remove={this.remove} items={this.state.items} />

        <form className="filter" onSubmit={this.handleSubmit}>
          <fieldset>
            <legend>Filter</legend>
            <div className="form-grp">
              <select name="type" onChange={this.onChangeType}>
                <option>foo</option>
                <option>bar</option>
                <option>baz</option>
              </select>
            </div>
          </fieldset>
          <div className="actions">
            <button>{'Add #' + (this.state.items.length + 1)}</button>
          </div>
        </form>
      </div>
    );
  }
});

React.render(<FilterApp />, document.body);