JuniorTheoryCommon

What does tsc report, and what does the program print?

TypeScript

const data: any = JSON.parse('{"price": 100}');
console.log(data.price.toFixed(2));
console.log(data.cost.toFixed(2));

tsc is silent; it prints 100.00, then a TypeError

Expecting tsc to notice the missing cost: data is any, so tsc checks none of its properties, and the mistake shows up only at run time.
Expecting undefined on the last line: data.cost is undefined, and calling toFixed on undefined throws a TypeError.

JuniorTheoryCommon

TypeScript

const data: any = JSON.parse('{"price": 100}');
console.log(data.price.toFixed(2));
console.log(data.cost.toFixed(2));

tsc is silent; it prints 100.00, then a TypeError

Expecting tsc to notice the missing cost: data is any, so tsc checks none of its properties, and the mistake shows up only at run time.
Expecting undefined on the last line: data.cost is undefined, and calling toFixed on undefined throws a TypeError.