获取范围的开始和结束偏移量相对于其父容器

Question

假设我有这个HTML元素:

<div id="parent">
 Hello everyone! <a>This is my home page</a>
 <p>Bye!</p>
</div>

用户用鼠标选择"家".

我希望能够确定#parent他的选择中有多少个字符开始(以及#parent他选择结束时有多少个字符结束).即使他选择了HTML标记,这也应该有效.(我需要它在所有浏览器中工作)

range.startOffset 看起来很有希望,但它只是相对于范围的直接容器的偏移量,并且仅当容器是文本节点时才是字符偏移量.

Answer 1

UPDATE

正如评论中指出的那样,我的原始答案(下面)仅返回选择结束或插入符号位置.调整代码以返回开始和结束偏移量相当容易; 这是一个这样做的例子:

function getSelectionCharacterOffsetWithin(element) {
    var start = 0;
    var end = 0;
    var doc = element.ownerDocument || element.document;
    var win = doc.defaultView || doc.parentWindow;
    var sel;
    if (typeof win.getSelection != "undefined") {
        sel = win.getSelection();
        if (sel.rangeCount > 0) {
            var range = win.getSelection().getRangeAt(0);
            var preCaretRange = range.cloneRange();
            preCaretRange.selectNodeContents(element);
            preCaretRange.setEnd(range.startContainer, range.startOffset);
            start = preCaretRange.toString().length;
            preCaretRange.setEnd(range.endContainer, range.endOffset);
            end = preCaretRange.toString().length;
        }
    } else if ( (sel = doc.selection) && sel.type != "Control") {
        var textRange = sel.createRange();
        var preCaretTextRange = doc.body.createTextRange();
        preCaretTextRange.moveToElementText(element);
        preCaretTextRange.setEndPoint("EndToStart", textRange);
        start = preCaretTextRange.text.length;
        preCaretTextRange.setEndPoint("EndToEnd", textRange);
        end = preCaretTextRange.text.length;
    }
    return { start: start, end: end };
}

function reportSelection() {
  var selOffsets = getSelectionCharacterOffsetWithin( document.getElementById("editor") );
  document.getElementById("selectionLog").innerHTML = "Selection offsets: " + selOffsets.start + ", " + selOffsets.end;
}

window.onload = function() {
  document.addEventListener("selectionchange", reportSelection, false);
  document.addEventListener("mouseup", reportSelection, false);
  document.addEventListener("mousedown", reportSelection, false);
  document.addEventListener("keyup", reportSelection, false);
};

#editor {
  padding: 5px;
  border: solid green 1px;
}

Select something in the content below:

<div id="editor" contenteditable="true">A <i>wombat</i> is a marsupial native to <b>Australia</b></div>
<div id="selectionLog"></div>

这是一个函数,它将获得指定元素中插入符的字符偏移量; 然而,这是一个天真的实现,几乎肯定会与换行符不一致,并且不会尝试处理通过CSS隐藏的文本(我怀疑IE会正确地忽略这些文本,而其他浏览器则不会).妥善处理所有这些东西会很棘手.我现在尝试将它用于我的Rangy库.

实例:http://jsfiddle.net/TjXEG/900/

function getCaretCharacterOffsetWithin(element) {
    var caretOffset = 0;
    var doc = element.ownerDocument || element.document;
    var win = doc.defaultView || doc.parentWindow;
    var sel;
    if (typeof win.getSelection != "undefined") {
        sel = win.getSelection();
        if (sel.rangeCount > 0) {
            var range = win.getSelection().getRangeAt(0);
            var preCaretRange = range.cloneRange();
            preCaretRange.selectNodeContents(element);
            preCaretRange.setEnd(range.endContainer, range.endOffset);
            caretOffset = preCaretRange.toString().length;
        }
    } else if ( (sel = doc.selection) && sel.type != "Control") {
        var textRange = sel.createRange();
        var preCaretTextRange = doc.body.createTextRange();
        preCaretTextRange.moveToElementText(element);
        preCaretTextRange.setEndPoint("EndToEnd", textRange);
        caretOffset = preCaretTextRange.text.length;
    }
    return caretOffset;
}

Answer 2

我知道这已经有一年了,但这篇文章是关于找到Caret职位的很多问题的最佳搜索结果,我觉得这很有用.

在内容可编辑div中将元素从一个位置拖放到另一个位置后,我试图使用Tim上面的优秀脚本来查找新的光标位置.它在FF和IE中完美运行,但在Chrome中,拖动操作突出显示拖动开始和结束之间的所有内容,这导致返回caretOffset的太大或太小(按所选区域的长度).

我在第一个if语句中添加了几行来检查文本是否已被选中并相应地调整结果.新的声明如下.请原谅我在这里添加这个是不合适的,因为这不是OP试图做的事情,但正如我所说的那样,对Caret职位相关信息的几次搜索引导我进入这篇文章,所以它(希望)可能会帮助其他人.

蒂姆的第一个if语句添加了行(*):

if (typeof window.getSelection != "undefined") {
  var range = window.getSelection().getRangeAt(0);
  var selected = range.toString().length; // *
  var preCaretRange = range.cloneRange();
  preCaretRange.selectNodeContents(element);
  preCaretRange.setEnd(range.endContainer, range.endOffset);

  if(selected){ // *
    caretOffset = preCaretRange.toString().length - selected; // *
  } else { // *
    caretOffset = preCaretRange.toString().length; 
  } // *
}

Answer 3

经过几天的试验，我发现了一种很有前途的方法。因为selectNodeContents()不处理<br>正确的标签，我写了一个自定义的算法来确定每个文本长度node内contenteditable。为了计算例如选择开始，我总结了所有先前节点的文本长度。这样，我可以处理（多个）换行符：

var editor = null;
var output = null;

const getTextSelection = function (editor) {
    const selection = window.getSelection();

    if (selection != null && selection.rangeCount > 0) {
        const range = selection.getRangeAt(0);

        return {
            start: getTextLength(editor, range.startContainer, range.startOffset),
            end: getTextLength(editor, range.endContainer, range.endOffset)
        };
    } else
        return null;
}

const getTextLength = function (parent, node, offset) {
    var textLength = 0;

    if (node.nodeName == '#text')
        textLength += offset;
    else for (var i = 0; i < offset; i++)
        textLength += getNodeTextLength(node.childNodes[i]);

    if (node != parent)
        textLength += getTextLength(parent, node.parentNode, getNodeOffset(node));

    return textLength;
}

const getNodeTextLength = function (node) {
    var textLength = 0;

    if (node.nodeName == 'BR')
        textLength = 1;
    else if (node.nodeName == '#text')
        textLength = node.nodeValue.length;
    else if (node.childNodes != null)
        for (var i = 0; i < node.childNodes.length; i++)
            textLength += getNodeTextLength(node.childNodes[i]);

    return textLength;
}

const getNodeOffset = function (node) {
    return node == null ? -1 : 1 + getNodeOffset(node.previousSibling);
}

window.onload = function () {
    editor = document.querySelector('.editor');
    output = document.querySelector('#output');

    document.addEventListener('selectionchange', handleSelectionChange);
}

const handleSelectionChange = function () {
    if (isEditor(document.activeElement)) {
        const textSelection = getTextSelection(document.activeElement);

        if (textSelection != null) {
            const text = document.activeElement.innerText;
            const selection = text.slice(textSelection.start, textSelection.end);
            print(`Selection: [${selection}] (Start: ${textSelection.start}, End: ${textSelection.end})`);
        } else
            print('Selection is null!');
    } else
        print('Select some text above');
}

const isEditor = function (element) {
    return element != null && element.classList.contains('editor');
}

const print = function (message) {
    if (output != null)
        output.innerText = message;
    else
        console.log('output is null!');
}

* {
    font-family: 'Georgia', sans-serif;
    padding: 0;
    margin: 0;
}

body {
    margin: 16px;
}

.p {
    font-size: 16px;
    line-height: 24px;
    padding: 0 2px;
}

.editor {
    border: 1px solid #0000001e;
    border-radius: 2px;
    white-space: pre-wrap;
}

#output {
    margin-top: 16px;
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="./script.js" async></script>
    <link href="./stylesheet.css" rel="stylesheet">
    <title>Caret Position</title>
</head>
<body>
    <p class="editor" contenteditable="true"><em>Write<br></em><br>some <br>awesome <b><em>text </em></b>here...</p>
    <p id="output">Select some text above</p>
</body>
</html>