Null, Undefined, Symbol, and BigInt Types
You have already learned about the main primitive types in TypeScript like number, string, and boolean. However, TypeScript also provides a few less common but important primitive types: null, undefined, symbol, and bigint. These types play unique roles in your code and allow for more precise type safety and advanced use cases.
The null and undefined types represent the absence of a value. In JavaScript, variables that have not been assigned a value are undefined, while null is an explicit assignment that means "no value." TypeScript distinguishes between these two, and you can use them directly as types.
The symbol type is used to create unique identifiers, often for object property keys that should not clash with others.
The bigint type allows you to work with very large integers, beyond the safe range of the regular number type.
index.ts
When you enable strict null checks in your TypeScript configuration (with "strictNullChecks": true), TypeScript will not allow null or undefined to be assigned to other types unless you explicitly include them in a union. This helps prevent common bugs related to missing values.
Use the symbol type when you need unique property keys for objects, especially in cases like implementing custom behavior in libraries or frameworks. Use the bigint type when you need to safely handle integers larger than Number.MAX_SAFE_INTEGER (which is 2^53 - 1), such as for cryptography, scientific calculations, or working with large IDs.
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You have already learned about the main primitive types in TypeScript like number, string, and boolean. However, TypeScript also provides a few less common but important primitive types: null, undefined, symbol, and bigint. These types play unique roles in your code and allow for more precise type safety and advanced use cases.
The null and undefined types represent the absence of a value. In JavaScript, variables that have not been assigned a value are undefined, while null is an explicit assignment that means "no value." TypeScript distinguishes between these two, and you can use them directly as types.
The symbol type is used to create unique identifiers, often for object property keys that should not clash with others.
The bigint type allows you to work with very large integers, beyond the safe range of the regular number type.
index.ts
When you enable strict null checks in your TypeScript configuration (with "strictNullChecks": true), TypeScript will not allow null or undefined to be assigned to other types unless you explicitly include them in a union. This helps prevent common bugs related to missing values.
Use the symbol type when you need unique property keys for objects, especially in cases like implementing custom behavior in libraries or frameworks. Use the bigint type when you need to safely handle integers larger than Number.MAX_SAFE_INTEGER (which is 2^53 - 1), such as for cryptography, scientific calculations, or working with large IDs.
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