In TypeScript, type inference and generic type with default serve different purposes, and the compiler prioritizes type inference over generic type with default when it comes to determining the actual type of a variable or function parameter.

  1. Type Inference: Type inference is the process by which TypeScript automatically determines the type of a variable based on its initialization value or how it's used. When you declare a variable without explicitly specifying its type, TypeScript will attempt to infer the type from the value assigned to it.

    For example:

    const foo = 42; // TypeScript infers that 'foo' is of type 'number' const bar = "hello"; // TypeScript infers that 'bar' is of type 'string'

    Type inference takes precedence over explicitly assigned types, as TypeScript aims to minimize the need for explicit type annotations.

  2. Generic Type with Default: TypeScript allows you to define generic types that can take one or more type parameters. You can also provide default types for these type parameters in case they are not explicitly specified during usage.

    For example:

    function identity<T = any>(arg: T): T { return arg; } const result = identity(42); // TypeScript infers that 'result' is of type 'number'

    In this example, identity is a generic function that takes a type parameter T with a default value of any. When you call the identity function without explicitly specifying the type, TypeScript infers the type based on the argument passed to the function.

    However, if you explicitly specify the type during the function call, the specified type will take precedence over the default:

    const result = identity<string>("hello"); // 'result' is of type 'string'

In summary, TypeScript prioritizes type inference to allow for more concise and readable code. It infers types from the values and expressions used in your code whenever possible. Generic types with default are a mechanism to provide flexibility and control over the types used in generic functions or classes, but they don't override type inference when TypeScript can determine the type from the context.

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