var result = string.trim().split(", ").map(el=>el.split("|").map(n=>+n))
this splits the string into an array of these groups ( yet as string )
"1|2, 3|4" => ["1|2","3|4"]
then maps this array to a new array containing the strings splitted and converted to numbers:
=> [[1,2],[3,4]]
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solved Convert string into several integer arrays [duplicate]