Equality Utilities

The Equality utilities provide functions for comparing values and objects in JavaScript. These functions offer more comprehensive equality checks than the built-in equality operators, particularly for complex data structures.

Functions

isEqual

function isEqual(a, b, options?)

Performs a deep equality comparison between two values.

Deep Comparison This function performs a recursive comparison for objects and arrays, ensuring that nested structures are also checked for equality. It handles various edge cases, including NaN comparisons. A class instance compares by its own equals() when both operands carry one, the convention Temporal, Immutable.js and Luxon share, so two Temporal.Instant values are equal when they mark the same instant.

Parameters

Name	Type	Description
a	any	The first value to compare
b	any	The second value to compare
options	object	Optional comparison options

Options

Name	Type	Default	Description
loose	boolean	`false`	Uses `==` instead of `===` for leaf value comparison
ignoreKeys	string[]	`[]`	Array of property names to skip during comparison, at the top level only
deepIgnore	boolean	`false`	Applies `ignoreKeys` at every depth instead of just the top level
partial	boolean	`false`	Checks if `a` is a structural subset of `b`

Returns

boolean - true if the values are deeply equal, false otherwise.

Example

import { isEqual } from '@semantic-ui/utils';

console.log(isEqual({a: 1, b: {c: 2}}, {a: 1, b: {c: 2}})); // true
console.log(isEqual([1, 2, 3], [1, 2, 3])); // true
console.log(isEqual({a: 1, b: 2}, {b: 2, a: 1})); // true
console.log(isEqual(NaN, NaN)); // true
console.log(isEqual({a: 1, b: 2}, {a: 1, b: 3})); // false
console.log(isEqual(Temporal.Instant.from('2026-09-06T14:30Z'), Temporal.Instant.from('2026-09-06T14:30Z'))); // true (by its own equals)

Loose Comparison

When loose is true, leaf values are compared with == instead of ===, allowing type coercion.

import { isEqual } from '@semantic-ui/utils';

console.log(isEqual('1', 1, { loose: true })); // true
console.log(isEqual(0, false, { loose: true })); // true
console.log(isEqual('1', 1)); // false (strict by default)

Ignoring Keys

Use ignoreKeys to skip specific properties during comparison.

import { isEqual } from '@semantic-ui/utils';

const a = { name: 'Alice', updatedAt: 1000 };
const b = { name: 'Alice', updatedAt: 2000 };

console.log(isEqual(a, b)); // false
console.log(isEqual(a, b, { ignoreKeys: ['updatedAt'] })); // true

Partial Comparison

When partial is true, checks if a is a structural subset of b — every key in a must exist and match in b, but b may have additional keys.

import { isEqual } from '@semantic-ui/utils';

const subset = { a: 1 };
const full = { a: 1, b: 2, c: 3 };

console.log(isEqual(subset, full)); // false
console.log(isEqual(subset, full, { partial: true })); // true
console.log(isEqual(full, subset, { partial: true })); // false (a has keys b doesn't)

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