Javascript，如何重新创建选择/范围？

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我在下面这样做：我需要抓住一个网页选择，然后再重新确定选择。当原始选择被创建为前进时，这可以工作，但是当通过向后/向上移动鼠标进行原始选择时，此功能不起作用。它不会出错，但没有选择。在这种情况下，我需要切换setStart（）和setEnd（）的参数。

我如何知道我需要这样做？原来的选择是向后的，还是一个节点在另一个节点之后/之前？

编辑：我想使用普通的js，没有额外的库

编辑2：我不需要这个工作在旧的IE。 IE9 +很好。

// ****用户选择 // *** *获取选择和范围**** var selection = window.getSelection（）; var startNode = selection.anchorNode; var endNode = selection.focusNode; var startOffset = selection.anchorOffset; var endOffset = selection.focusOffset; // ****做选择丢失的东西***** // ****重新选择，因为它是**** var range = document.createRange（）; range.setStart（startNode，startOffset）; range.setEnd（endNode，endOffset）; selection.removeAllRanges（）; selection.addRange（range）; //作品，除非原始选择是向后的

解决方案

像我需要的：

x = startNodepareDocumentPosition（endNode）; if（x == 4 ||（x == 0&& startOffset< endOffset））{ range.setStart（startNode，startOffset）; range.setEnd（endNode，endOffset）; } else { range.setStart（endNode，endOffset）; range.setEnd（startNode，startOffset）; }

我不认为这在旧版浏览器中有效，但对我来说。

In javascript: I need to grab a webpage selection, and then recreate the exact selection later.

I do this as below. This works when the original selected is created forwards, but not when the original selection is made by moving the mouse backwards/up. It does not throw an error, but nothing is selected. In this case, I need to switch the parameters for setStart() and setEnd().

How do I know that I need to do this? That the original selection was backwards or that one node comes after/before the other?

EDIT: I'd like to use plain js, no extra libraries

EDIT 2: I do not need this to work in old IE. IE9+ is fine.

// **** user makes selection // **** get selection and range **** var selection = window.getSelection(); var startNode = selection.anchorNode; var endNode = selection.focusNode; var startOffset = selection.anchorOffset; var endOffset = selection.focusOffset; // **** do stuff where selection is lost ***** // **** recreate selection as it was **** var range = document.createRange(); range.setStart(startNode, startOffset); range.setEnd(endNode, endOffset); selection.removeAllRanges(); selection.addRange(range); // works except when original selection was backwards

解决方案

It looks like I need:

x = startNodepareDocumentPosition(endNode); if (x == 4 || (x==0 && startOffset < endOffset)){ range.setStart(startNode, startOffset); range.setEnd(endNode, endOffset); }else{ range.setStart(endNode, endOffset); range.setEnd(startNode, startOffset); }

I don't think this works in older browsers, but it's fine for me.