react 自动查询_React和自动对焦

野性酷女 2023-02-21 14:26 29阅读 0赞

react 自动查询

While I love ReactJS, I can say that I sometimes find interactions that were easy during the pre-ReactJS are annoyingly difficult or at least "indirect".  One example is properly ensuring that a given `<input>` element gets focused when a button in a different component is clicked; in the old days, it was three lines of code, but with React it can be more.

虽然我喜欢ReactJS，但我可以说有时候我发现在ReactJS之前很容易进行的交互非常麻烦，或者至少是“间接”的。 一个例子是正确地确保当单击不同组件中的按钮时，给定的`<input>`元素会集中； 在过去，这是三行代码，但是使用React可以更多。

Let's have a look at a few strategies for properly focusing on `<input>` elements with ReactJS.

让我们看一下使用ReactJS正确关注`<input>`元素的一些策略。

## `autofocus` **(**`autofocus`**)** ##

The `autofocus` attribute is honored in ReactJS but only when the `<input>` element is re-rendered with React:

在ReactJS中使用`autofocus`属性，但仅当使用React重新渲染`<input>`元素时：

`autofocus` is easy to use but only works when the `<input>` is initially rendered; since React intelligently only re-renders elements that have changed, the `autofocus` attribute isn't reliable in all cases.

`autofocus`易于使用，但仅在最初呈现`<input>` ； 由于React只能智能地重新渲染已更改的元素，因此`autofocus`属性在所有情况下都不可靠。

## 具有`ref` `componentDidUpdate` **(**`componentDidUpdate` with `ref`**)** ##

Since we can't rely solely on the `autofocus` attribute, we can use `componentDidUpdate` to complete the focus:

由于我们不能仅依赖于`autofocus`属性，因此可以使用`componentDidUpdate`来完成焦点：

class Expressions extends Component {
    
      _input: ?HTMLInputElement;
    
      // ....
    
      componentDidUpdate(prevProps, prevState) {
        this._input.focus();
      }
    
      render() {
          return (
            <div className={this.state.focused ? "focused": ""}>
                <input
                  autofocus="true"
                  ref={c => (this._input = c)}
                />
            </div>
          );
        }
      }
    }

`componentDidUpdate` fires after the component is updated, so any change to the parent component would trigger this method and your `<input>` would receive focus.  In my cases, I usually toggle a `className` on the parent element to signal the element is active and thus the `componentDidUpdate` will trigger.

`componentDidUpdate`更新后将触发componentDidUpdate，因此对父组件的任何更改都将触发此方法，并且您的`<input>`将获得焦点。 就我而言，我通常在父元素上切换一个`className` ，以表明该元素处于活动状态，因此`componentDidUpdate`将触发。

My perspective of inter-widget interaction has been formed by the days of Dojo's dijit UI framework where each widget usually had a reference to every child widget; with ReactJS the practice is (hopefully) avoiding `ref`s and using `state`, which is logical but there's still that piece of me that longs for a simple reference, which is why the second strategy makes sense to me.

我对小部件间交互的观点是在Dojo的dijit UI框架时代形成的，每个小部件通常都有对每个子小部件的引用。 使用ReactJS的做法是(希望)避免使用`ref`并使用`state` ，这是合乎逻辑的，但是我当中仍然有人渴望获得简单的引用，这就是第二种策略对我有意义的原因。

> 翻译自: [https://davidwalsh.name/react-autofocus][https_davidwalsh.name_react-autofocus]

react 自动查询

[https_davidwalsh.name_react-autofocus]: https://davidwalsh.name/react-autofocus