What is the difference between `ts.SyntaxKind.VariableStatement` and `ts.SyntaxKind.FirstStatement`

Question

They both share the same enum value e.g. from TypeScript 3.7.2:

VariableStatement = 224,
FirstStatement = 224,

Why are there two names for the same syntax kind?

Answer 1

In the SyntaxKind enum, there are some entries which are used to denote not the concrete syntax kind, but a class of them. For statements, it is defined as following:

enum SyntaxKind {
    // snip
    FirstStatement = VariableStatement,
    LastStatement = DebuggerStatement,
    // snip
}

Then, to check if some syntax kind is one of the "statement" kinds, one can simply write kind >= SyntaxKind.FirstStatement && kind <= SyntaxKind.LastStatement. And, if the set of statement kinds will ever change, only the definition of FirstStatement or LastStatement should be changed, not these "range checks".