Function compareFields

  • compareFields<ObjectType>(
        ...fields: FieldSpec<ObjectType>[],
    ): Comparator<ObjectType>

  • Creates a new comparator function that compares the fields of its input arguments using the given specification. The function can then be used, for example, in calls to Array.sort().

    Type Parameters

    • ObjectType

    Parameters

    • ...fields: FieldSpec<ObjectType>[]

      A list of fields that specify the object comparison. This can be a direct field name or an object specifier for advanced configuration. Multiple field names or objects are also supported, in which case the new comparator will create a lexicographic order based on these fields.

      A field name is considered to be a string for member attributes, or a number to indicate a particular index of an array within the array to be sorted.

      The default comparison function compares fields using the builtin < and > operators, but a custom compare function can be specified when using the object notation.

      The order returned by the comparator is ascending by default.

    Returns Comparator<ObjectType>

    the new comparator function.

    Example: _Sort by age, then by name_

    const data = [
      { name: "B", age: 21 },
      { name: "A", age: 21 },
      { name: "C", age: 20 }
    ];
    // Orders by age, or if ages are equal, by name.
    data.sort(compareFields("age", "name"));

    Example: _Reverse sort order for a single field_

    const data = [
      { name: "B", age: 21 },
      { name: "A", age: 21 },
      { name: "C", age: 20 }
    ];
    data.sort(compareFields({ field: "age", reverse: true }, "name"));

    Example: _Compare array items using indices as field "names"_

    const data = [
      [1, 2],
      [1, 3],
      [2, 3],
    ];
    // Orders by array item at index 1, or by index 0 if the other values are equal.
    data.sort(compareFields(1, 0));

    Example: _Compare field values with a custom comparator_

    const compare = (a, b) => b - a; // Some custom comparison logic
    const data = [
      { value: 3 },
      { value: 4 },
    ];
    // Compares value using the custom comparison function
    data.sort(compareFields({ field: "value", compare: compare }));

    Example: _Compare field values with a custom value picker_

    const valuePicker = (a) => a.value ?? 0; // Some custom value lookup logic, e.g. default values
    const data = [
      { value: 3 },
      { value: 4 },
    ];
    // Compares value using the custom comparison function
    data.sort(compareFields({ valuePicker }));

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