Assignment (. +?) In regular expressions

Question

I am new to this thing.

When analyzing code, I often come across a template .+?or(.+?)

I can not find the meaning of this template using my deductive reasoning noobish.

Answer 1

.means any character (except a new line). +means one or more. ?in this context mean lazy or inanimate. This means that he will try to match the absolute minimum of characters that satisfy the quantifier. Example:

> 'abc'.match(/.+/)
["abc"]
> 'abc'.match(/.+?/)
["a"]
> 'abc'.match(/.*/)
["abc"]
> 'abc'.match(/.*?/)
[""]

Answer 2

, . , , , :

• .
• + 1
• .+
• ? ungreedy, , .

:

/.+X/.exec("aaaXaaaXaaa");
["aaaXaaaX"]
/.+?X/.exec("aaaXaaaXaaa");
["aaaX"]

, ? , , .