What does this TypeScript snippet output?

Console output

Why

A tagged template calls `tag` with a `TemplateStringsArray` of the static string chunks (`["a", "b"]`) followed by each interpolated value (`2`). The function rebuilds the result as `s[0] + x + s[1]`, giving `"a2b"`. `TemplateStringsArray` is the precise TypeScript type for that first argument, capturing the raw literal segments at compile time.