AssociateTo

AssociateTo[a, key -> val] changes the association a by adding the key-value pair key->val.

AssociateTo[a, {key1 -> val1, key2 -> val2, ...}] adds all key-value pairs keyi->vali.

Examples

Add a key-value pair:

a = <|"x" -> 1|>;
AssociateTo[a, "y" -> 2]
(* <|"x" -> 1, "y" -> 2|> *)

Add multiple pairs:

AssociateTo[a, {"z" -> 3, "w" -> 4}]
(* <|"x" -> 1, "y" -> 2, "z" -> 3, "w" -> 4|> *)

Please visit the official Wolfram Language Reference for more details.