在 HTML 中选择后保持范围对象的变化

Persisting the changes of range objects after selection in HTML(在 HTML 中选择后保持范围对象的变化)

问题描述

有没有办法保存更改，例如更改跨越多个标签的 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.

Is there a way to save the changes like changing the background of HTML text that span over multiple tags so that when it is loaded again the changes made should be reflected in the HTML page.

详细说明.

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

When the HTML page is loaded, the text is selected and highlighted using the range object and the executeCommand:

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

在重新加载页面之前，更改(将文本突出显示为黄色)会一直保留.但是当页面重新加载时，这些更改不存在.我想要以某种方式保存这些更改，例如在本地 DB sqlite 中，以便在重新加载/刷新页面时，应该出现 HTML 页面中的更改.

The changes (highlighting the text as yellow) remain until the page is reloaded. But when the page is reloaded these changes are not there. What i want is to save somehow these changes like in local DB sqlite so that when page is reloaded/refreshed the changes in HTML page should appear.

知道怎么做.我是否需要保存其范围开始偏移量和结束偏移量，以便在下次加载页面时创建范围.请提供您的见解.

Any idea how to do it. Do i need to save its range start offset and end offset which can be used to create range next time the page is loaded. Please give your insights.

推荐答案

对于每个选择，您可以将所选范围序列化为字符偏移量，并在重新加载时使用类似这样的方法再次反序列化:

For each selection, you could serialize the selected range to character offsets and deserialize it again on reload using something like this:

演示:http://jsfiddle.net/WeWy7/3/

代码:

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();
    };
}

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