Function: equals()

Deeply compares two values, returning true if they're equal and false otherwise. The following criteria are used to determine equality:

• All values are equal to themselves.
• Primitives a and b are equal iff Object.is(a, b). This is similar to === comparison, but treats NaN as equal to NaN and 0 as different from -0.
• Dates are equal iff they have the same millisecond-precision timestamp.
• RegExps are equal iff they have the same pattern and flags.
• Errors are equal iff they have the same class and message.
• Arrays are equal iff they have the same length and their corresponding elements are equal (according to equals).
• Sets are equal iff they contain the same elements. Note that set elements are not deeply compared.
• Maps are equal iff they have the same set of keys, and their corresponding values are deeply equal. Note that map keys are not deeply compared.
• Partially applied functions (via curry or partial-apply) are equal iff they originate from the same function and their bound arguments are equal according to equals.
• Other objects are equal iff they have the same prototype (e.g. the same class) and the same set of enumerable string-keyed properties, and the values of their corresponding properties are equal (according to equals).

You can customize how equals() compares values of a specific class by using the $equals symbol to define a method on that class. For example:

import {$equals} from "@longlast/symbols";

class HttpError extends Error {
    private statusCode: number;
    constructor(message: string, statusCode: number) {
        super(message);
        this.statusCode = statusCode;
    }

    [$equals](other: unknown) {
        return other instanceof HttpError &&
            other.statusCode === this.statusCode &&
            other.message === this.message;
    }
}

Note that this makes the comparison asymmetrical: a is considered equal to b iff a[$equals](b) returns truthy. The $equals method will always be called on the first argument to equals().

equals() is curried. See curry.

Limitations

equals() can throw a RangeError if one of its arguments contains a reference cycle. Avoid passing mutable objects to equals() unless you know that they do not contain cycles.

Call Signature

equals(a: unknown, b: unknown): boolean

Defined in: pkg/equals/src/index.ts:236

Parameters

Returns

boolean

Call Signature

equals(a: unknown): Curried1<unknown, boolean>

Defined in: pkg/equals/src/index.ts:236

Parameters

Returns

Curried1<unknown, boolean>