Solutions to IE BUG and string interception substr_Basic knowledge

I haven’t paid attention to this problem until now, but I wanted to do something like this today:

Copy code The code is as follows:

var str = 'hello world 8024';

str.substr(-4,4);

Negative numbers count down from the end.

should return: 8024

But I found that in IE6-IE8, the substr parameter does not support negative numbers, and the returned value is: hell. You can test it.

So, we still do not recommend using this substr method.
Let’s use the substring method instead.

For example: str.substring(str.length-4);
will return correctly: 8024