Strict configuration objects in Typescript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean for a configuration object to be strict in TypeScript?

A strict configuration object means it must exactly match the expected shape with no extra or missing properties. TypeScript enforces this to catch errors early.

beginner

How does TypeScript behave when you pass an object with extra properties to a function expecting a strict configuration object?

TypeScript will give a type error because extra properties are not allowed in strict configuration objects. This helps prevent bugs from unexpected options.

intermediate

What TypeScript feature helps enforce strict configuration objects by disallowing extra properties?

TypeScript's excess property checks combined with object literal type checking enforces strict configuration objects by flagging extra properties as errors.

beginner

Why might you want to use strict configuration objects in your TypeScript code?

Using strict configuration objects helps catch mistakes early, ensures your code uses only expected options, and improves code clarity and maintainability.

intermediate

How can you allow optional properties in a strict configuration object without losing strictness?

You can mark properties as optional using ? in the type definition. This keeps strictness but allows those properties to be omitted.

What happens if you pass an object with an extra property to a function expecting a strict configuration object in TypeScript?

A TypeScript shows an error for the extra property.

B TypeScript ignores the extra property silently.

C The extra property overwrites existing ones.

D The function runs but with a warning.

TypeScript enforces strict configuration objects by showing an error when extra properties are present.

How do you mark a property as optional in a strict configuration object type?

A Use 'undefined' as the property type.

B Use a question mark (?) after the property name.

C Use the keyword 'optional' before the property.

D You cannot have optional properties in strict objects.

In TypeScript, adding '?' after a property name marks it as optional.

Which TypeScript feature helps catch extra properties in configuration objects?

A Type assertions

B Type inference

C Excess property checks

D Union types

Excess property checks flag extra properties not expected in the type.

Why is using strict configuration objects beneficial?

A It prevents bugs by ensuring only expected options are used.

B It makes the code run faster.

C It allows any properties without errors.

D It disables type checking.

Strict configuration objects help prevent bugs by enforcing expected properties only.

If you want to allow extra properties in a configuration object, what should you do?

A You cannot allow extra properties.

B Mark all properties as optional.

C Use a union type.

D Use an index signature like [key: string]: any.

An index signature allows extra properties by specifying a flexible key and value type.

Explain what a strict configuration object is in TypeScript and why it is useful.

Think about how TypeScript checks object shapes when passing them as arguments.

Describe how to define optional properties in a strict configuration object type and why you might want to do that.

Optional properties let you skip some settings but still keep type safety.