javascript drawing rectangular box_javascript skills

If you don't consider encapsulating the entire code, you can write a similar effect in about 5 minutes. In order to encapsulate the entire code into an object, I slightly borrowed the style of the example in the Pro Javascript Techniques book.
Recommended drag and drop examples in the Pro Javascript Techniques book: http://boring.youngpup.net/2001/domdrag

<title>Rect</title> <style type="text/css"> </style> <div id="main" style="border: solid red 1px; height:90%; width:60%; curssor: default;"> </div> <input type="button" value="停止绘画" id="t"> Add a button to turn off the painting effect, used to test the deletion function
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If you need to introduce external Js, you need to refresh to execute ]