2019-04-22 使用字符串生成正则表达式注意问号的双重转义,然后用来split

定义一个从字符串生成正则表达式的函数:

function getRegex(str) {
    return new RegExp(str, "ig");
}

测试使用问号作为参数的结果, 报错了,和日志中错误相同:

getRegex("?")
VM50:2 Uncaught SyntaxError: Invalid regular expression: /?/: Nothing to repeat
    at new RegExp ()
    at getRegex (:2:12)
    at :1:1
getRegex @ VM50:2
(anonymous) @ VM66:1

尝试转义问号呢?

getRegex("\?")
VM50:2 Uncaught SyntaxError: Invalid regular expression: /?/: Nothing to repeat
    at new RegExp ()
    at getRegex (:2:12)
    at :1:1
getRegex @ VM50:2
(anonymous) @ VM69:1

再次使用转义, 可以了

getRegex("\\?")
/\?/gi

其他情况?

getRegex("??")
VM50:2 Uncaught SyntaxError: Invalid regular expression: /??/: Nothing to repeat
    at new RegExp ()
    at getRegex (:2:12)
    at :1:1
getRegex @ VM50:2
(anonymous) @ VM77:1

使用中括号表示可选?

getRegex("[?]")
/[?]/gi

str="https://visteria.vnative.net/5cb08a1689d4466c7080723c?p1={your-transaction-id}&source={your-sub-aff-id}"
"https://visteria.vnative.net/5cb08a1689d4466c7080723c?p1={your-transaction-id}&source={your-sub-aff-id}"

把正则表达式用来做split的参数

aa=getRegex("[?]")
/[?]/gi

str.split(aa)
(2) ["https://visteria.vnative.net/5cb08a1689d4466c7080723c", "p1={your-transaction-id}&source={your-sub-aff-id}"]

str.split(aa)[0]
"https://visteria.vnative.net/5cb08a1689d4466c7080723c"

最后重复一次对比

aa=getRegex("?")
VM50:2 Uncaught SyntaxError: Invalid regular expression: /?/: Nothing to repeat
    at new RegExp ()
    at getRegex (:2:12)
    at :1:4
getRegex @ VM50:2
(anonymous) @ VM153:1

aa=getRegex("\?")
VM50:2 Uncaught SyntaxError: Invalid regular expression: /?/: Nothing to repeat
    at new RegExp ()
    at getRegex (:2:12)
    at :1:4
getRegex @ VM50:2
(anonymous) @ VM156:1

aa=getRegex("\\?")
/\?/gi

str.split(aa)[0]
"https://visteria.vnative.net/5cb08a1689d4466c7080723c"

str.split(aa)
(2) ["https://visteria.vnative.net/5cb08a1689d4466c7080723c", "p1={your-transaction-id}&source={your-sub-aff-id}"]