在 contenteditable 插入符位置考虑 `<br>`

Question

为了获取和设置 contenteditable 元素中的插入符位置，我已经尝试了 this answer 中的代码，但是开始和结束位置会随着您移动到不同的文本节点而重置。

<div contenteditable>012345<br><br><br>9012345</div>

所以，我修改了 this answer (by @TimDown) but it's still not quite counting the line breaks properly... In this demo 的代码，当我在 4 之后单击并按三下向右箭头时，我将看到 start/end 报告为 5、6，然后是 8。或者，使用鼠标从第一行的 4 开始 select 并继续向右 selecting（参见 gif）

这是代码（demo；尽管看起来像，jQuery 没有被使用）

function getCaret(el) {
  let start, end;
  const range = document.getSelection().getRangeAt(0),
    preSelectionRange = range.cloneRange(),
    postSelectionRange = range.cloneRange();
  preSelectionRange.selectNodeContents(el);
  preSelectionRange.setEnd(range.startContainer, range.startOffset);
  postSelectionRange.selectNodeContents(el);
  postSelectionRange.setEnd(range.endContainer, range.endOffset);
  start = preSelectionRange.toString().length;
  end = start + range.toString().length;
  // count <br>'s and adjust start & end
  if (start > 0) {
    var node,
      i = el.children.length;
    while (i--) {
      node = el.children[i];
      if (node.nodeType === 1 && node.nodeName === 'BR') {
        start += preSelectionRange.intersectsNode(el.children[i]) ? 1 : 0;
        end += postSelectionRange.intersectsNode(el.children[i]) ? 1 : 0;
      }
    }
  }
  return {start, end};
}

setCaret 函数修改似乎工作正常（在这个基本的内容可编辑示例中）。

function setCaret(el, start, end) {
  var node, i, nextCharIndex, sel,
    charIndex = 0,
    nodeStack = [el],
    foundStart = false,
    stop = false,
    range = document.createRange();
  range.setStart(el, 0);
  range.collapse(true);
  while (!stop && (node = nodeStack.pop())) {
    // BR's aren't counted, so we need to increase the index when one
    // is encountered 
    if (node.nodeType === 1 && node.nodeName === 'BR') {
      charIndex++;
    } else if (node.nodeType === 3) {
      nextCharIndex = charIndex + node.length;
      if (!foundStart && start >= charIndex && start <= nextCharIndex) {
        range.setStart(node, start - charIndex);
        foundStart = true;
      }
      if (foundStart && end >= charIndex && end <= nextCharIndex) {
        range.setEnd(node, end - charIndex);
        stop = true;
      }
      charIndex = nextCharIndex;
    } else {
      i = node.childNodes.length;
      while (i--) {
        nodeStack.push(node.childNodes[i]);
      }
    }
  }
  sel = document.getSelection();
  sel.removeAllRanges();
  sel.addRange(range);
}

我可以使用一些 advice/help 解决以下问题：

如何正确计算 <br> 秒？

如何计算开头的<br>（在此HTML示例中）？

<div contenteditable><br>12345<br><br><br>9012345</div>

将 <br> 包裹在 <div> 中（在此 HTML 示例中）- 我最终会讲到这一点，但我没有想继续沿着这条路走下去，发现有更简单的方法。
```
<div contenteditable><div><br></div>12345<div><br></div><div><br></div><div><br></div>9012345</div>
```
我试图用rangy替换上面的代码，但它似乎没有内置方法来获取或设置范围。

Answer 1

我修改了您的演示，将位置序列化为 container/offset 对，而不仅仅是一个位置。容器被序列化为一个简单的索引数组，进入每个节点的 childNodes 集合，从一个参考节点开始（在本例中当然是 contenteditable 元素）。

我不太清楚你打算用它做什么，但由于它反映了选择模型，它应该会给你带来更少的痛苦。

const $el = $('ce'),
  $startContainer = $('start-container'),
  $startOffset = $('start-offset'),
  $endContainer = $('end-container'),
  $endOffset = $('end-offset');
  
function pathFromNode(node, reference) {
  function traverse(node, acc) {
    if (node === reference) {
      return acc;
    } else {
      const parent = node.parentNode;
      const index = [...parent.childNodes].indexOf(node);
      return traverse(parent, [index, ...acc]);
    }
  }
  return traverse(node, []);
}

function nodeFromPath(path, reference) {
  if (path.length === 0) {
    return reference;
  } else {
    const [index, ...rest] = path;
    const next = reference.childNodes[index];
    return nodeFromPath(rest, next);
  }
}

function getCaret(el) {
  const range = document.getSelection().getRangeAt(0);
  return {
    start: {
      container: pathFromNode(range.startContainer, el),
      offset: range.startOffset
    },
    end: {
      container: pathFromNode(range.endContainer, el),
      offset: range.endOffset
    }
  };
}

function setCaret(el, start, end) {
  const range = document.createRange();
  range.setStart(nodeFromPath(start.container, el), start.offset);
  range.setEnd(nodeFromPath(end.container, el), end.offset);
  sel = document.getSelection();
  sel.removeAllRanges();
  sel.addRange(range);
}

function update() {
  const pos = getCaret($el);
  $startContainer.value = JSON.stringify(pos.start.container);
  $startOffset.value = pos.start.offset;
  $endContainer.value = JSON.stringify(pos.end.container);
  $endOffset.value = pos.end.offset;
}

$el.addEventListener('keyup', update);
$el.addEventListener('click', update);

$('set').addEventListener('click', () => {
  const start = {
    container: JSON.parse($startContainer.value),
    offset: $startOffset.value
  };
  const end = {
    container: JSON.parse($endContainer.value),
    offset: $endOffset.value
  };
  setCaret($el, start, end);
});

function $(sel) {
  return document.getElementById(sel);
}

input {
  width: 40px;
}

[contenteditable] {
  white-space: pre;
}

(updates on click &amp; keyup)<br/>
<label>Start: <input id="start-container" type="text"/><input id="start-offset" type="number"/></label><br/>
<label>End: <input id="end-container" type="text"/><input id="end-offset" type="number"/></label><br/>
<button id="set">Set</button>
<p></p>
<!-- inline BR's behave differently from <br> on their own separate line
<div id="ce" contenteditable>012345<br><br><br>9012345</div>
-->

<!-- get/set caret needs to work with these examples as well
* <br> at beginning
  <div id="ce" contenteditable><br>12345<br><br><br>9012345</div>
* <br>'s wrapped in a <div>
-->
  <div id="ce" contenteditable><div><br></div>12345<div><br></div><div><br></div><div><br></div>9012345</div>

在 contenteditable 插入符位置考虑 `<br>`

Accounting for `<br>`s in contenteditable caret position

javascript

ecmascript-6

contenteditable

caret