Function rest

Alias

  • rest<F>(func, startIndex?): ((...args: any[]) => ReturnType<F>)

  • Creates a function that transforms the arguments of the provided function func. The transformed arguments are passed to func such that the arguments starting from a specified index are grouped into an array, while the previous arguments are passed as individual elements.

    Type Parameters

    • F extends ((...args: any[]) => any)

      The type of the function being transformed.

    Parameters

    • func: F

      The function whose arguments are to be transformed.

    • OptionalstartIndex: number

      The index from which to start grouping the remaining arguments into an array. Defaults to func.length - 1, grouping all arguments after the last parameter.

    Returns ((...args: any[]) => ReturnType<F>)

    A new function that, when called, returns the result of calling func with the transformed arguments.

    The transformed arguments are:

    • The first start arguments as individual elements.
    • The remaining arguments from index start onward grouped into an array.
      • (...args): ReturnType<F>

      • Parameters

        • Rest...args: any[]

        Returns ReturnType<F>

    Example

    function fn(a, b, c) {
      return [a, b, c];
    }

    // Using default start index (func.length - 1, which is 2 in this case)
    const transformedFn = rest(fn);
    console.log(transformedFn(1, 2, 3, 4)); // [1, 2, [3, 4]]

    // Using start index 1
    const transformedFnWithStart = rest(fn, 1);
    console.log(transformedFnWithStart(1, 2, 3, 4)); // [1, [2, 3, 4]]

    // With fewer arguments than the start index
    console.log(transformedFn(1)); // [1, undefined, []]

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