字符串的正则表达式以X开头并包含Y. [英] regex for string starts with X and contains Y

问题描述

我正在尝试编写一个构建正则表达式的函数，该函数可以测试字符串是否以字符串开头并包含另一个字符串。

I am trying to write a function that builds a regular expression that can test whether a string starts with a string and contains another string.

function buildRegExp(startsWith,contains){
    return new RegExp( ????? )
}

例如：

buildRegExp('abc','fg').test('abcdefg')

上面的表达式应该评估为true，因为字符串'abcdefg'以''开头' abc'并包含'fg'。

The above expression should evaluate to true, since the string 'abcdefg' starts with 'abc' and contains 'fg'.

'startsWith'和'contains'字符串可能相互重叠，因此正则表达式不能简单地搜索'startsWith'字符串，然后搜索'contains'字符串

The 'startsWith', and the 'contains' strings may overlap eachother, so the regular expression cannot simply search for the 'startsWith' string, then search for 'contains' string

以下内容也应评估为true：

the following should also evaluate to true:

buildRegExp('abc','bcd').test('abcdefg')

我不能使用简单的字符串函数。它需要是一个正则表达式，因为我将这个正则表达式传递给MongoDB查询。

I cannot use simple string functions. It needs to be a regular expression because I am passing this regular expression to a MongoDB query.

推荐答案

这样的模式会处理 startsWith / 包含匹配字符串中的子字符串重叠的情况：

A pattern like this would handle cases where the startsWith / contains substrings overlap in the matched string:

/(?=.*bcd)^abc/

ie

return new RegExp("(?=.*" + contains + ")^" + startsWith);

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