TypeScript
Also written as TS
A superset of JavaScript that adds static typing, catching certain bugs before the code even runs.
Think of it like
Like labeled outlets on that wiring — '120V only' — so you get a warning before plugging in the wrong thing, instead of finding out the hard way.
Junior or senior?
Junior sounds like
Uses TypeScript's defaults without adjusting them.
Senior sounds like
Can describe how strict they keep their config, and a time they deliberately loosened it to ship faster.
Ask them
“How strict do you keep your TypeScript config, and have you ever loosened it just to ship faster?”
Sounds like real experience
Names a specific type they had to model — a discriminated union, a generic, a tricky third-party type — or a real bug TypeScript's type-checking actually caught before runtime.
Probe further if
Describes TypeScript only as 'JavaScript with types' without a specific example of a type-related bug it caught, or a config tradeoff they made under deadline pressure.