Jmeter Extracting inside square bracket value only

Hello Can someone please help me extract only the value inside of square bracket. Your response is highly appreciated. Thanks and in advance.

Sample Response: var outline = {"12881":[205085,205105,205106,206407,210551,210552,210553,210554,210555,210556,210557,210558,210559,210560,210561,210562,210563,210826,210827],"12775":[205088,205089,205104,205153],"12781":[205090],"12782":[205091],"12783":[205092],"12784":[205093],"12785":[205094],"12882":[205095,208016,210678],"12883":[205096,206410],"12884":[205097,208017],"12885":[205098,208018],"12836":[205099,208324],"12886":[205100,208019,208020,208021],"12806":[205101,208330],"12807":[205102],"12810":[205103,208333],"12779":[205107],"12780":[205108,205109],"12805":[205110,208329],"12839":[205112,205113,205160,205161],"12789":[205114,205115],"12786":[205116,208201,208202,208203,208204,208205],"12816":[205127],"12788":[205128],"12811":[205129,205130,205131],"12815":[205132],"12794":[205157,208323],"12809":[205159],"12787":[206408,208206,208207,208208,208209,208210,208211],"12889":[206413,206414,206415],"12832":[206416,208189,208190,208191,208192,208193,208194,208195,208196,208197],"12833":[206417,206418,206419,206420,208198,208199,208200],"12890":[206421,206422,206423,206424,206425,206426,206427,206428],"12835":[206429,206430,206431,206432],"12834":[206433,206434,206435,206436],"12891":[206437,206438,206439,206440,206441,206442],"12887":[208058],"12888":[208059],"12965":[208183,208184,208185,208186,208187],"12933":[208188],"12812":[208212,208213],"12813":[208214,208215,208216],"12814":[208217,208218,208219],"12820":[208220,208221,208222],"12821":[208224,208225],"12819":[208226,208227],"12939":[208228,208229,208230,208231],"12940":[208232,208233],"12844":[208316,208317,208318],"12790":[208319,208325],"12791":[208320,208326],"12792":[208321,208327],"12793":[208322,208328],"12808":[208331,208332],"13058":[209018,209019,209021],"13036":[210621,210622,210623,210628],"13037":[210629],"13199":[210742,210743,210744,210745,210755,210756,210757,210758],"13038":[210828,210829,210830]};

Expected result:
205085,205105,205106,206407,210551,210552,210553,210554,210555,210556,210557,210558,210559,210560,210561,210562,210563,210826,210827
-205088,205089,205104,205153
-205091
-205092
and so on

values inside of the square bracket are dynamic. I just want to extra all values inside square bracket or "[ ]"

Solution

I think it would be easier to use JSR223 PostProcessor and JsonSlurper, the relevant code would be something like:

def json = new groovy.json.JsonSlurper().parse(prev.getResponseData())
def counter = 1
json.each { entry ->
    entry.getValue().each { number ->
        vars.put('value_' + counter, number as String)
        counter++
    }
}

Demo:

More information: