在javascript中在所选文本的每一行之前插入文本

Question

我有一些文字，我可以在选择之前和之后添加我的文字：

Hello, I can insert text before and after this by javascript.

1. How to insert text

2. before each line

a. if text is separeted by /g

对于环绕声选择我正在使用此代码：

function surroundSelection(textBefore, textAfter, color) {

    if (window.getSelection) {
    var sel = window.getSelection();
    var selectedText = sel.toString();
    if(selectedText.trim() != "") {

            if (sel.rangeCount > 0) {
            var range = sel.getRangeAt(0);
            var startNode = range.startContainer, startOffset = range.startOffset;

            var startTextNode   = document.createElement(\'span\');
            startTextNode.style.backgroundColor = color;
            var startTextNode_t = document.createTextNode(textBefore);
            startTextNode.appendChild(startTextNode_t);

            var endTextNode   = document.createElement(\'span\');
            endTextNode.style.backgroundColor = color;
            var endTextNode_t = document.createTextNode(textAfter);
            endTextNode.appendChild(endTextNode_t);

            var boundaryRange = range.cloneRange();
            boundaryRange.collapse(false);
            boundaryRange.insertNode(endTextNode);
            boundaryRange.setStart(startNode, startOffset);
            boundaryRange.collapse(true);
            boundaryRange.insertNode(startTextNode);

            range.setStartAfter(startTextNode);
            range.setEndBefore(endTextNode);

            sel.removeAllRanges();
            sel.addRange(range);

            }
        }

    }
    }

选择文字后的结果可以是：

**!!its_my_text_start!!**Hello, I can insert text before and after this by javascript.

1. How to insert text

2. before each line **!!its_my_text_end!!**

a. if text is separeted by /g

但现在我需要选择列表的文本，并将我的文本放在每个元素的开头和结尾处，由/ g分隔。

例如：

Hello, I can insert text before and after this by javascript.

**El_1_start** 1. How to insert text **El_1_end**

**El_2_start** 2. before each line **El_2_end**

**El_3_start** a. if text is separeted by /g **El_3_end**

如何使用window.getSelection？

执行此操作