+ 字符在正则表达式中具有特殊意义。这是一个量词，意思是一个或多个上一个字符，字符类或组的内容。

The + character has special significance in regular expressions. It's a quantifier meaning one or more of the previous character, character class, or group.

您需要转义 + ，如下所示：

You need to escape the +, like this:

i.replace(new RegExp("\\+","g"),' ')...

或者更简单地说，通过使用预编译表达式：

Or more simply, by using a precompiled expression:

i.replace(/\+/g,' ')...