javascript - 为什么在单击按钮时从 textarea 中获取文本选择有效，但在单击 "div"时无效(在 Internet Explorer 中)

Question

考虑以下代码:( Live demo here - Open in Internet Explorer 7 or 9 )

HTML:

<textarea>Hello Stack Overflow</textarea>
<input class="a" type="button" value="Click here does the job" />
<div class="a">But clicking here not :(</div>

JS:

    function getInputSelection(el) {
    var start = 0, end = 0, normalizedValue, range, textInputRange, len, endRange;

    if (typeof el.selectionStart == "number" && typeof el.selectionEnd == "number") {
        start = el.selectionStart;
        end = el.selectionEnd;
    } else {
        range = document.selection.createRange();

        if (range && range.parentElement() == el) {
            len = el.value.length;
            normalizedValue = el.value.replace(/\r\n/g, "\n");

            // Create a working TextRange that lives only in the input
            textInputRange = el.createTextRange();
            textInputRange.moveToBookmark(range.getBookmark());

            // Check if the start and end of the selection are at the very end
            // of the input, since moveStart/moveEnd doesn't return what we want
            // in those cases
            endRange = el.createTextRange();
            endRange.collapse(false);

            if (textInputRange.compareEndPoints("StartToEnd", endRange) > -1) {
                start = end = len;
            } else {
                start = -textInputRange.moveStart("character", -len);
                start += normalizedValue.slice(0, start).split("\n").length - 1;

                if (textInputRange.compareEndPoints("EndToEnd", endRange) > -1) {
                    end = len;
                } else {
                    end = -textInputRange.moveEnd("character", -len);
                    end += normalizedValue.slice(0, end).split("\n").length - 1;
                }
            }
        }
    }

    return {start: start, end: end};
}


function getselection() {
  var selectedText = getInputSelection($("textarea")[0]);
  var start = selectedText.start;
  var end = selectedText.end;
  alert("Start: " + start + ", End: " + end);
}

$(".a").click(getselection);

getInputSelection()函数取自 here .

出于某种原因，当 <div>被点击，结果总是:

Start: 0, End: 0

有什么解决办法吗？

Answer 1

问题是点击 <div>在 getInputSelection() 之前失去对文本区域的关注函数执行。有两种选择:

• 要么使用 mousedown事件改为:http://jsfiddle.net/RbSLw/13/ , 或
• 制作<div>不可选择(通过在 IE 中添加 unselectable="on" 属性来完成):http://jsfiddle.net/RbSLw/14/ .