nonConsistent2DArray

function nonConsistent2DArray<T>(arr: T | Array<Array<unknown>>): arr is T;

nonConsistent2DArray(value) is the same test as !isConsistent2DArray(value), written so that a guard clause reads forwards — see Validation conventions.

Like non2DArray, it is best used for its boolean answer: after the check TypeScript does not hand back a usable matrix type. requireConsistent2DArray is what validates and returns the matrix.

It reports true for two different situations: a matrix whose rows differ in length, and a value that is not a matrix at all. They are indistinguishable from the result alone, so use non2DArray when the difference matters.

Parameters

Parameter	Type	Description
`arr`	`T \\| Array<Array<unknown>>`	The value to check.

Returns

boolean — true if the value is not a non-empty array of arrays of equal length; otherwise false.

In TypeScript the guard narrows arr to T inside the branch.

Examples

Both failing cases

nonConsistent2DArray([[1, 2], [3]]); // => true — ragged
nonConsistent2DArray([1, 2]); // => true — not 2D
nonConsistent2DArray([
  [1, 2],
  [3, 4]
]); // => false

Telling the two apart

/**
 * Tells the two failure cases apart: not a matrix at all, versus a matrix
 * whose rows differ in length.
 */
export function describeShape(rows: unknown): string {
  if (non2DArray(rows)) {
    return "not a matrix";
  }

  if (nonConsistent2DArray(rows)) {
    return "a matrix, but the rows differ in length";
  }

  return "ready for setValues";
}

function describeShape(rows) {
  if (non2DArray(rows)) {
    return "not a matrix";
  }
  if (nonConsistent2DArray(rows)) {
    return "a matrix, but the rows differ in length";
  }
  return "ready for setValues";
}

Source

src/lang/array/nonConsistent2DArray.ts

23 September 2026

This documentation was generated with AI (Claude) from the library's source code.

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