Regular expression pattern matching in JavaScript?

Question

Pattern matching in Javascript

I want to make pattern which matches the string

{"ABC":["A1","X30","2","A2","X31","3","A3","X90","9"],"XYZ":["A1","X31","2","A3","X40","7"]}

I have used regex pattern

{("["A-Z0-9"]+":["[A-Z0-9]+","[A-Z0-9]+","[0-9]+"],)+}

but it doesn't match properly.

Every array length is multiple of 3 only and first & second element in pair of 3 consist of [A-Z0-9] only and third element consist of [0-9] only.

For example: "A1","X30" (first two element) & "2"(third element) similarly after 3 elements this pattern repeats "A2","X31" as first and second element and "3" as third element.

test pattern-1:

{"ABC":["A1","X30","2"],"XYZ":["A1","X31","2","A3","X40","7"]}

test pattern-2:

{"ABC":["A1","X30","2","A2","X31","3","A3","X90","9"],"XYZ":["A1","X31","2","A3","X40","7"]}

test pattern-3:

{"ABC":["A1","X30","2"]}

The fourth bird · Accepted Answer · 2021-05-30 08:01:37Z

2

You have to optionally repeat the inner part with the 3 parts again:

{"["A-Z0-9"]+":["[A-Z0-9]+","[A-Z0-9]+","[0-9]+"(?:,"[A-Z0-9]+","[A-Z0-9]+","[0-9]+")*](?:,"["A-Z0-9"]+":["[A-Z0-9]+","[A-Z0-9]+","[0-9]+"(?:,"[A-Z0-9]+","[A-Z0-9]+","[0-9]+")*])*}

The pattern in parts:

{ Match opening {
"["A-Z0-9"]+":["[A-Z0-9]+","[A-Z0-9]+","[0-9]+" Match the part before the : followed by 3 parts after it consisting of 2 times [A-Z0-9] and only digits for the 3rd part
(?: Non capture group
- ,"[A-Z0-9]+","[A-Z0-9]+","[0-9]+"
)* Close non capture group and optionally repeat
] Match ]
(?: Non capture group
- ,"["A-Z0-9"]+":["[A-Z0-9]+","[A-Z0-9]+","[0-9]+" Match a again the part before the : and the 3 parts after it
- (?: Non capture group
  - ,"[A-Z0-9]+","[A-Z0-9]+","[0-9]+" Match a comma and repeat the first part again
- )* Close non capture group and optionally repeat
- ] Match ]
)* Close non capture group and optionally repeat
} Match closing }

Regex demo

edited May 30, 2021 at 8:01

answered May 30, 2021 at 7:54

The fourth bird

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3 Comments

Hemil Shah Over a year ago

{"ABC":["A1","X","2"]} It doesn't work on string like this because there should be a number followed by upper case letter in First and Second Element.

The fourth bird Over a year ago

Then you can replace the [A-Z0-9]+ parts with [A-Z][0-9]+ or the other way around.

Hemil Shah Over a year ago

I have changed [A-Z0-9]+ to [A-Z]+[0-9]+ and it works !! Thanks !!

logi-kal · Accepted Answer · 2021-05-30 07:57:28Z

2

This is a correct pattern:

{("[A-Z0-9]+":\[("[A-Z0-9]+","[A-Z0-9]+","[0-9]+"(,|(?=\])))+\](,|(?=})))+}

where (,|(?=\])) means "match a , or check that it is followed by a ]".

See a demo here.

Anyway, you should use a JSON parser if you want to be sure not to have unwanted behaviors.

answered May 30, 2021 at 7:57

logi-kal

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2 Comments

Hemil Shah Over a year ago

{"ABC":["A1","X","2"]} It doesn't work on string like this because there should be a number followed by upper case letter in First and Second Element

logi-kal Over a year ago

Then use {("[A-Z0-9]+":\[("[A-Z][0-9]+","[A-Z][0-9]+","[0-9]+"(,|(?=\])))+\](,|(?=})))+}

Alexander Kiselev · Accepted Answer · 2021-05-30 08:02:36Z

1

You can add sub groups.

{("[A-Z0-9]+":\[("[A-Z0-9]+","[A-Z0-9]+","[0-9]+",?)+\],?)+}

https://regex101.com/r/OqjcVv/1

answered May 30, 2021 at 8:02

Alexander Kiselev

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