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bool keyExists = m.ContainsKey(key)if (k in m) { }maps:is_key(K, M).Map.member k mAssumes m is an "actual" map,
m :: Map k v.
m :: Map k v.
(/=Nothing) (lookup k m)
_m.has(_k)Uses an actual Map instance, rather than relying on objects and their keys
m.hasOwnProperty(k)This is like "k in m" except it doesn't check up the prototype chain, which is often not what people want.
k in mThis will lookup a property in the object and its entire prototype chain.
(nth-value 1 (gethash k m))gethash returns a value, and a boolean for whether or not the entry is present.
m[k] ~= nilarray_key_exists($k, $m)m.IndexOf(k) >= 0This works for a number of Pascal containers, including TFPGMap.
exists $m->{$k}k in mm.get(k)"... If default is not given, it defaults to None"
m.contains(k)(assoc k m)m includesKey: k.If m.ContainsKey(k) Then...