JavaScript：使用Regex提取两个可选字符之间的字符串部分

Question

I'm working on a regex in javascript for capturing part of the string between two optional characters.

Optional characters are: '=' and '||'

Scenarios:

• LENGTH=A simple message||5
• LENGTH=A simple message
• LENGTH||5

For getting the value after '||' I manage that with the split() function.

For getting the 'A simple message' part I manage to extract the string with the regex match(/\\=(.*)\\|\\|/).pop() when both '=' and '||' are in the string.

Any suggestions for extracting the string with one regex when one of the two optional characters is there?

I tried also /(\\=)?(.*)(\\|\\|)?/ but is not working.

Answer 1

You can use this negative lookahead based regex to capture value from = and optional || :

/=((?:(?!\|\|).)*)/

RegEx Demo

Answer 2

This should probably do what you want:

^LENGTH(?:=([^|]*))?(?:\|\|(\d+))?$

This will match both the part between LENGTH= and || and the part after that. Both will be returned in the result, when present.

Example:

[
    "LENGTH=A simple message||5",
    "LENGTH=A simple message",
    "LENGTH||5"
].forEach(function(string)
{
    var result = string.match(/^LENGTH(?:=([^|]*))?(?:\|\|(\d+))?$/);
    console.log("found:",result[1],result[2]);
});

Of course, there are a few assumptions here regarding the actual format of the data.

Output:

found: A simple message / 5
found: A simple message / undefined
found: undefined / 5