Regular Expressions 101

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`
"pack_id": "(.*)"
`
img
"pack_id": "
matches the characters "pack_id": " literally (case insensitive)
1st Capturing Group
(.*)
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
" matches the character " with index 3410 (2216 or 428) literally (case insensitive)
Global pattern flags
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.

Regular Expression
No Match

`
`
img

Test String