doocs/leetcode · error · Error

Not Equal

Error message

Not Equal

What it means

English README TypeScript tab of LeetCode 2704: toBe(toBeVal) throws Error('Not Equal') on strict-equality failure between the constructor-captured val and the argument. It mirrors the Solution.ts behavior and documents that identity (for objects) and exact type+value (for primitives) are required.

Source

Thrown at solution/2700-2799/2704.To Be Or Not To Be/README_EN.md:73

<!-- solution:start -->

### Solution 1

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#### TypeScript

```ts
type ToBeOrNotToBe = {
    toBe: (val: any) => boolean;
    notToBe: (val: any) => boolean;
};

function expect(val: any): ToBeOrNotToBe {
    return {
        toBe: (toBeVal: any) => {
            if (val !== toBeVal) {
                throw new Error('Not Equal');
            }
            return true;
        },
        notToBe: (notToBeVal: any) => {
            if (val === notToBeVal) {
                throw new Error('Equal');
            }
            return true;
        },
    };
}

/**
 * expect(5).toBe(5); // true
 * expect(5).notToBe(5); // throws "Equal"
 */
```

View on GitHub (pinned to f84f361dc4)

Solutions

1. Normalize types before comparing
2. Use serialized deep comparison for structures
3. Special-case NaN with Number.isNaN
4. Use toThrow('Not Equal') in tests that intentionally demonstrate failure

Example fix

// before
expect(JSON.parse('"5"')).toBe(5); // throws

// after
expect(Number(JSON.parse('"5"'))).toBe(5); // true

if (Number(val) === Number(toBeVal) && typeof val === typeof toBeVal) { /* safe */ }

function sameTypeAndEqual(a: unknown, b: unknown): boolean { return typeof a === typeof b && a === b; }

try { expect(v).toBe(e); } catch (e) { if ((e as Error).message !== 'Not Equal') throw e; }

When it happens

Trigger: expect(5).toBe('5'), expect([1,2]).toBe([1,2]), expect(undefined).toBe(null), expect(NaN).toBe(NaN).

Common situations: Running README samples in a playground; translating from loosely-typed comparison habits; expecting array/object deep equality; values flowing in from JSON.parse keeping string types where numbers were assumed.

Related errors

• Not Equal
• Equal
• Equal
• Not Equal
• Equal

AI-assisted analysis of doocs/leetcode@f84f361dc4 (2026-08-27). Data as JSON: /api/errors/539e701228956ed5. Report an issue: GitHub.