在HTML中选择后,保持范围对象的更改

Question

有没有办法保存更改,例如更改跨越多个标记的HTML文本的背景,以便在再次加载时,所做的更改应反映在HTML页面中.

编辑:详细解释.

加载HTML页面时,使用范围对象和executeCommand选择并突出显示文本:

             document.execCommand("BackColor", false, 'yellow');

更改(将文本突出显示为黄色)保留,直到重新加载页面.但是当重新加载页面时,这些更改不存在.我想要的是以某种方式保存这些更改,如在本地数据库sqlite中,以便在重新加载/刷新页面时,应显示HTML页面中的更改.

知道如何做到这一点.我是否需要保存其范围起始偏移和结束偏移,可用于下次加载页面时创建范围.请提供您的见解.

Answer 1

对于每个选择,您可以将所选范围序列化为字符偏移,并在重新加载时使用以下内容再次反序列化:

演示:http://jsfiddle.net/WeWy7/3/

码:

var saveSelection, restoreSelection;

if (window.getSelection && document.createRange) {
    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
        };
    };

    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) {
    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
        }
    };

    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();
    };
}

Answer 2

如果光标位于新段落的开头，则无法使用字符偏移。下面的方法遍历 DOM 节点并计算所有节点的偏移量。它还单独处理开始和结束，以确保选择记住其确切位置。这是我在一个主要项目中使用的更新版本（请参阅最后的功能）：

/*
 Gets the offset of a node within another node. Text nodes are
 counted a n where n is the length. Entering (or passing) an
 element is one offset. Exiting is 0.
 */
var getNodeOffset = function(start, dest) {
  var offset = 0;

  var node = start;
  var stack = [];

  while (true) {
    if (node === dest) {
      return offset;
    }

    // Go into children
    if (node.firstChild) {
      // Going into first one doesn't count
      if (node !== start)
        offset += 1;
      stack.push(node);
      node = node.firstChild;
    }
    // If can go to next sibling
    else if (stack.length > 0 && node.nextSibling) {
      // If text, count length (plus 1)
      if (node.nodeType === 3)
        offset += node.nodeValue.length + 1;
      else
        offset += 1;

      node = node.nextSibling;
    }
    else {
      // If text, count length
      if (node.nodeType === 3)
        offset += node.nodeValue.length + 1;
      else
        offset += 1;

      // No children or siblings, move up stack
      while (true) {
        if (stack.length <= 1)
          return offset;

        var next = stack.pop();

        // Go to sibling
        if (next.nextSibling) {
          node = next.nextSibling;
          break;
        }
      }
    }
  }
};

// Calculate the total offsets of a node
var calculateNodeOffset = function(node) {
  var offset = 0;

  // If text, count length
  if (node.nodeType === 3)
    offset += node.nodeValue.length + 1;
  else
    offset += 1;

  if (node.childNodes) {
    for (var i=0;i<node.childNodes.length;i++) {
      offset += calculateNodeOffset(node.childNodes[i]);
    }
  }

  return offset;
};

// Determine total offset length from returned offset from ranges
var totalOffsets = function(parentNode, offset) {
  if (parentNode.nodeType == 3)
    return offset;

  if (parentNode.nodeType == 1) {
    var total = 0;
    // Get child nodes
    for (var i=0;i<offset;i++) {
      total += calculateNodeOffset(parentNode.childNodes[i]);
    }
    return total;
  }

  return 0;
};

var getNodeAndOffsetAt = function(start, offset) {
  var node = start;
  var stack = [];

  while (true) {
    // If arrived
    if (offset <= 0)
      return { node: node, offset: 0 };

    // If will be within current text node
    if (node.nodeType == 3 && (offset <= node.nodeValue.length))
      return { node: node, offset: Math.min(offset, node.nodeValue.length) };

    // Go into children (first one doesn't count)
    if (node.firstChild) {
      if (node !== start)
        offset -= 1;
      stack.push(node);
      node = node.firstChild;
    }
    // If can go to next sibling
    else if (stack.length > 0 && node.nextSibling) {
      // If text, count length
      if (node.nodeType === 3)
        offset -= node.nodeValue.length + 1;
      else
        offset -= 1;

      node = node.nextSibling;
    }
    else {
      // No children or siblings, move up stack
      while (true) {
        if (stack.length <= 1) {
          // No more options, use current node
          if (node.nodeType == 3)
            return { node: node, offset: Math.min(offset, node.nodeValue.length) };
          else
            return { node: node, offset: 0 };
        }

        var next = stack.pop();

        // Go to sibling
        if (next.nextSibling) {
          // If text, count length
          if (node.nodeType === 3)
            offset -= node.nodeValue.length + 1;
          else
            offset -= 1;

          node = next.nextSibling;
          break;
        }
      }
    }
  }
};

exports.save = function(containerEl) {
  // Get range
  var selection = window.getSelection();
  if (selection.rangeCount > 0) {
    var range = selection.getRangeAt(0);
    return {
      start: getNodeOffset(containerEl, range.startContainer) + totalOffsets(range.startContainer, range.startOffset),
      end: getNodeOffset(containerEl, range.endContainer) + totalOffsets(range.endContainer, range.endOffset)
    };
  }
  else
    return null;
};

exports.restore = function(containerEl, savedSel) {
  if (!savedSel)
    return;

  var range = document.createRange();

  var startNodeOffset, endNodeOffset;
  startNodeOffset = getNodeAndOffsetAt(containerEl, savedSel.start);
  endNodeOffset = getNodeAndOffsetAt(containerEl, savedSel.end);

  range.setStart(startNodeOffset.node, startNodeOffset.offset);
  range.setEnd(endNodeOffset.node, endNodeOffset.offset);

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

这仅适用于现代浏览器（至少 IE 9+）。