React：编辑 contentEditable div 时如何保持插入符号位置？

Question

目前

1. 我有一个 react 组件，newValue当用户单击 contentEditable 时<div>，它会存储一个，并newValue随着用户键入而更新。注意：我以这种方式设置此行为有两个主要原因：（1）我不想发送要在每次击键时保存的数据，以及（2）我计划使用此 div 的变体，其中检查每个输入以验证输入是否为数字。
2. 在newValue发送时，要保存<div>失去焦点，然后道具的状态复位。

问题

将onChangeHandler可编辑 div 中插入符号的位置移动到左侧。这导致击键123456显示为654321

代码：

class Input extends Component {

  constructor(props) {
    super(props);
    this.state = {
      //newValue input by user
      newValue : undefined
    }
  }

  //handler during key press / input
  onChangeHandler = event => {
    let targetValue =  event.currentTarget.textContent;
    this.setState({"newValue": targetValue})
  }

  //handler when user opens input form
  onBlurHandler = event => {
    //some code that sends the "newValue" to be saved, and resets state
  }

  render() {
    //determine which value to show in the div
    let showValue;
    //if there is a new value being input by user, show this value
    if (this.state.newValue !== undefined) {
      showValue = this.state.newValue;
    } else {
      //if prop has no value e.g. null or undefined, use "" placeholder
      if (this.props.value) {
        showValue = this.props.value;
      } else {
        showValue = "";
      }
    }

    return (
    <table>
    <tbody>
      <td>
          <div
            contentEditable="true"
            suppressContentEditableWarning="true"
            onInput={this.onChangeHandler.bind(this)}
            onBlur={this.onBlurHandler}
          >{showValue}
          </div>
      </td>
     </tbody>
     </table>
    )
  }
}

export default Input;

笔记

1. 我以前用一个<textarea>没有这个问题的方法来做这个，但是<div>为了更好地控制自动调整 div 高度行为（参考CSS：Remove scroll bar and replace with variable height for textarea in a table <td>）
2. 我已经能够找到许多相关的答案，但没有一个是特定于反应的，例如在 contenteditable div 中保持光标位置。我假设因为每次笔画后 react 都在重新加载组件，所以发生了这个问题。
3. 我以前没有 ChangeHandler onInput，这工作正常，但我无法记录每个按键并验证字符是否为数字。

Answer 1

我能够按照/sf/answers/976526351/ 中的解决方案进行工作

主要变化：

1. 添加EditCaretPositioning.js具有 2 个功能的新组件：(1) saveSelection 以保存插入符位置，以及 (2) restoreSelection 以恢复插入符位置。
2. 在Input组件状态中保存插入符号位置
3. saveSelection()在每个Change事件之后调用
4. restoreSelection() 作为设置状态后的回调
5. 添加id到<div>so可以在restoreSelection()函数中引用

编辑CaretPositioning.js

const EditCaretPositioning = {}

export default EditCaretPositioning;


if (window.getSelection && document.createRange) {
    //saves caret position(s)
    EditCaretPositioning.saveSelection = function(containerEl) {
        var range = window.getSelection().getRangeAt(0);
        var preSelectionRange = range.cloneRange();
        preSelectionRange.selectNodeContents(containerEl);
        preSelectionRange.setEnd(range.startContainer, range.startOffset);
        var start = preSelectionRange.toString().length;

        return {
            start: start,
            end: start + range.toString().length
        }
    };
    //restores caret position(s)
    EditCaretPositioning.restoreSelection = function(containerEl, savedSel) {
        var charIndex = 0, range = document.createRange();
        range.setStart(containerEl, 0);
        range.collapse(true);
        var nodeStack = [containerEl], node, foundStart = false, stop = false;

        while (!stop && (node = nodeStack.pop())) {
            if (node.nodeType === 3) {
                var nextCharIndex = charIndex + node.length;
                if (!foundStart && savedSel.start >= charIndex && savedSel.start <= nextCharIndex) {
                    range.setStart(node, savedSel.start - charIndex);
                    foundStart = true;
                }
                if (foundStart && savedSel.end >= charIndex && savedSel.end <= nextCharIndex) {
                    range.setEnd(node, savedSel.end - charIndex);
                    stop = true;
                }
                charIndex = nextCharIndex;
            } else {
                var i = node.childNodes.length;
                while (i--) {
                    nodeStack.push(node.childNodes[i]);
                }
            }
        }

        var sel = window.getSelection();
        sel.removeAllRanges();
        sel.addRange(range);
    }



} else if (document.selection && document.body.createTextRange) {
  //saves caret position(s)
    EditCaretPositioning.saveSelection = function(containerEl) {
        var selectedTextRange = document.selection.createRange();
        var preSelectionTextRange = document.body.createTextRange();
        preSelectionTextRange.moveToElementText(containerEl);
        preSelectionTextRange.setEndPoint("EndToStart", selectedTextRange);
        var start = preSelectionTextRange.text.length;

        return {
            start: start,
            end: start + selectedTextRange.text.length
        }
    };
    //restores caret position(s)
    EditCaretPositioning.restoreSelection = function(containerEl, savedSel) {
        var textRange = document.body.createTextRange();
        textRange.moveToElementText(containerEl);
        textRange.collapse(true);
        textRange.moveEnd("character", savedSel.end);
        textRange.moveStart("character", savedSel.start);
        textRange.select();
    };

}

更新了 contentEditable div 组件：

import CaretPositioning from 'EditCaretPositioning'

class Input extends Component {

  constructor(props) {
    super(props);
    this.state = {
      //newValue input by user
      newValue : undefined,
      //stores positions(s) of caret to handle reload after onChange end
      caretPosition : {
        start : 0,
        end : 0
      }
    }
  }

  //handler during key press / input
  onChangeHandler = event => {
    let targetValue =  event.currentTarget.textContent;
    //save caret position(s), so can restore when component reloads
    let savedCaretPosition = CaretPositioning.saveSelection(event.currentTarget);
    this.setState({
      "newValue": targetValue,
      "caretPosition" : savedCaretPosition
    }, () => {
      //restore caret position(s)
      CaretPositioning.restoreSelection(document.getElementById("editable"), this.state.caretPosition);
    })
  }

  //handler when user opens input form
  onBlurHandler = event => {
    //some code that sends the "newValue" to be saved, and resets state
  }

  render() {
    //determine which value to show in the div
    let showValue;
    //if there is a new value being input by user, show this value
    if (this.state.newValue !== undefined) {
      showValue = this.state.newValue;
    } else {
      //if prop has no value e.g. null or undefined, use "" placeholder
      if (this.props.value) {
        showValue = this.props.value;
      } else {
        showValue = "";
      }
    }

    return (
    <table>
    <tbody>
      <td>
          <div
            id="editable"
            contentEditable="true"
            suppressContentEditableWarning="true"
            onInput={this.onChangeHandler.bind(this)}
            onBlur={this.onBlurHandler}
          >{showValue}
          </div>
      </td>
     </tbody>
     </table>
    )
  }
}

export default Input;