te')); return $arr; } /* 遍历用户所有主题 * @param $uid 用户ID * @param int $page 页数 * @param int $pagesize 每页记录条数 * @param bool $desc 排序方式 TRUE降序 FALSE升序 * @param string $key 返回的数组用那一列的值作为 key * @param array $col 查询哪些列 */ function thread_tid_find_by_uid($uid, $page = 1, $pagesize = 1000, $desc = TRUE, $key = 'tid', $col = array()) { if (empty($uid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('uid' => $uid), array('tid' => $orderby), $page, $pagesize, $key, $col); return $arr; } // 遍历栏目下tid 支持数组 $fid = array(1,2,3) function thread_tid_find_by_fid($fid, $page = 1, $pagesize = 1000, $desc = TRUE) { if (empty($fid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('fid' => $fid), array('tid' => $orderby), $page, $pagesize, 'tid', array('tid', 'verify_date')); return $arr; } function thread_tid_delete($tid) { if (empty($tid)) return FALSE; $r = thread_tid__delete(array('tid' => $tid)); return $r; } function thread_tid_count() { $n = thread_tid__count(); return $n; } // 统计用户主题数 大数量下严谨使用非主键统计 function thread_uid_count($uid) { $n = thread_tid__count(array('uid' => $uid)); return $n; } // 统计栏目主题数 大数量下严谨使用非主键统计 function thread_fid_count($fid) { $n = thread_tid__count(array('fid' => $fid)); return $n; } ?>javascript - React toggle component - Stack Overflow

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    javascript - React toggle component - Stack Overflow

    programmeradmin4浏览0评论

    I have this simple code below. When I press the Toggle Button the ponent Child should hide/show, but it's not.

    Do I have to re-render something? I don't want to switch in/out a CSS class, just toggle via a button click

    import React, {Component} from 'react';

let active = true

const handleClick = () => {
    active = !active
}

class Parent extends React.Component {
    render() {      
        return (    
            <div>  
                <OtherComponent />

                {active && <Child />}

                <button type="button" onClick={handleClick}>
                    Toggle
                </button>

            </div>            
        )           
    }
}

class Child extends React.Component {
    render() {

        return (    
            <div>          
                I am the child
            </div>            
        )             
    }
}

class OtherComponent extends React.Component {
    render() {       
        return (    
            <div>          
                I am the OtherComponent
            </div>            
        )           
    }
}

    I have this simple code below. When I press the Toggle Button the ponent Child should hide/show, but it's not.

    Do I have to re-render something? I don't want to switch in/out a CSS class, just toggle via a button click

    import React, {Component} from 'react';

let active = true

const handleClick = () => {
    active = !active
}

class Parent extends React.Component {
    render() {      
        return (    
            <div>  
                <OtherComponent />

                {active && <Child />}

                <button type="button" onClick={handleClick}>
                    Toggle
                </button>

            </div>            
        )           
    }
}

class Child extends React.Component {
    render() {

        return (    
            <div>          
                I am the child
            </div>            
        )             
    }
}

class OtherComponent extends React.Component {
    render() {       
        return (    
            <div>          
                I am the OtherComponent
            </div>            
        )           
    }
}
    • javascript
    • reactjs
    Share Improve this question edited Apr 28, 2019 at 6:33 Sagiv b.g 31k10 gold badges72 silver badges104 bronze badges asked May 18, 2017 at 13:06 RoryRory 1,4924 gold badges21 silver badges38 bronze badges 1
    • Possible duplicate of Show or hide element in React – Damjan Pavlica Commented May 8, 2018 at 12:02
    Add a ment  | 

    2 Answers 2

    Reset to default 7

    You need to get or set it via state: 

    class Parent extends React.Component {
    constructor(props, context) {
        super(props, context);

        this.state = {
            active: true,
        };

        this.handleClick = this.handleClick.bind(this);
    }

    handleClick() {
        this.setState({
            active: !this.state.active
        });
    }

    render() {
        return (
            <div>
                <OtherComponent />

                {this.state.active && <Child />}

                <button type="button" onClick={this.handleClick}>
                    Toggle
                </button>

            </div>
        )
    }
}

    Note that with this approach you will re:render the entire parent ponent (as well as it's children).
    Consider using another approach, when you are passing a prop to the child ponent and it will render itself with content based on this prop (it can render an empty div or something).
    There are number of libraries that make this job easy for you, like react-collapse with animations and stuff.

    You should only use state and props to manage your app state.

    So instead try:

    class Parent extends React.Component {
  constructor(props, context) {
    super(props, context);
    this.state = {
        active: true
    };
    this.handleClick = this.handleClick.bind(this);
  }

  const handleClick = () => {
    this.setState({active = !this.state.active});
  }

  render() {      
    return (    
      <div>  
        <OtherComponent />
        {this.state.active && <Child />}
        <button type="button" onClick={handleClick}>
          Toggle
        </button>
      </div>            
    );          
  }
}

    Alernatively, you could use forceUpdate() to force a re-render, but this is strongly discouraged:

    const handleClick = () => {
  active = !active;
  this.forceUpdate();
}

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