JavaScript provides a typeof operator that can examine a value and tell you what type it is:
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var a;typeof a; // "undefined"a = "hello world";typeof a; // "string"a = 42;typeof a; // "number"a = true;typeof a; // "boolean"a = null;typeof a; // "object" -- weird, buga = undefined;typeof a; // "undefined"a = { b: "c" };typeof a; // "object"OUTPUT
:001 > Cmd/Ctrl-Enter to run, Cmd/Ctrl-/ to comment