Parsing array syntax using regex in javascript

Question

I found the answer for this here but it's in php.

I would like to match an array like [123, "hehe", "lala"] but only if the array syntax is correct.

I made this regex /\\["?.+"?(?:,"?.+"?)*\\]/ .

The problem is that if the input is [123, "hehe, "lala"] , the regex match, but the syntax is incorrect.

How can I make it only match if the array syntax is correct?

My problem is making the second " required when the first " is matched.

Edit: I'm only trying to do it only with strings and numbers inside the array.

Answer 1

You can try this regex: /\\[((\\d+|"([^"]|\\\\")*?")\\s*,?\\s*)*(?<!,)\\]/

Each item should either

"([^"]|\\\\")*?" : start and end with ", containing anything but ". If " is contained it should be escaped (\\").

\\d+ : a number

After each item should be

\\s*,?\\s* : a comma with any number of spaces before or after.

And before the closing bracket should not be a comma: (?<!,)

Demo: https://regex101.com/r/jRAQUc/1

Answer 2

You must have two (or more) separate expressions (using the | operator) in order to do that.

So it would be something like this:

/\[\s*("[^"]*"|[0-9]+)(\s*,\s*("[^"]*"|[0-9]+))*\s*\]/

(You may also want to use ^ at the start and $ at the end to make sure nothing else appears before/after the array: /^...snip...$/ to match the string from start to finish.)

If you need floating point numbers with exponents, add a period and the 'e' character: [0-9.eE]+ (which is why I did not use \\d+ because only digits are allowed in that case.) To make sure a number is valid, it's much more complicated, obviously (sign, exponent with/without sign, digits only before or after the decimal point...)

You could also support single quoted strings. That too is a separate expression: '[^']*' .

You may want to allow spaces before and after the brackets too (start: /^\\s*\\[... and end: ...\\]\\s*$/ ).

Finally, if you want to really support JavaScript strings you would need to add support for the backslash. Something like this: ("([^"]|\\\\.)*") .

Note

Your .+ expression would match " and , too and without the ^ and $ an array as follow matches your expression just fine:

This Array ["test", 123, true, "this"] Here