isEmptyArray

Determines whether a value is an empty array with enhanced type safety. Performs dual validation to ensure the value is both an array and has zero length, providing reliable empty array detection for array processing and validation scenarios.

Signature

const isEmptyArray: (value: unknown) => boolean

Parameters

Name	Type	Description
value	-	Value to test for empty array characteristics

Returns

Type-safe boolean indicating whether the value is an empty array

Examples

Empty array detection

import { isEmptyArray } from '@winglet/common-utils';

// True cases - empty arrays
console.log(isEmptyArray([])); // true
console.log(isEmptyArray(new Array())); // true
console.log(isEmptyArray(Array.from(''))); // true

// False cases - not empty arrays
console.log(isEmptyArray([1, 2, 3])); // false (has elements)
console.log(isEmptyArray([undefined])); // false (has one element)
console.log(isEmptyArray([''])); // false (has one empty string element)
console.log(isEmptyArray(null)); // false (not an array)
console.log(isEmptyArray(undefined)); // false (not an array)
console.log(isEmptyArray({})); // false (object, not array)
console.log(isEmptyArray('')); // false (empty string, not array)
console.log(isEmptyArray({ length: 0 })); // false (array-like, not array)

Array processing with empty check

function processDataList(data: unknown) {
  if (isEmptyArray(data)) {
    console.log('No data to process');
    return { processed: 0, results: [] };
  }

  if (Array.isArray(data)) {
    // Process non-empty array
    const results = data.map((item, index) => {
      return { index, value: item, processed: true };
    });

    return { processed: results.length, results };
  }

  throw new Error('Expected array data');
}

Form validation

interface FormData {
  tags: unknown;
  categories: unknown;
  items: unknown;
}

function validateArrayFields(formData: FormData) {
  const errors: string[] = [];

  if (isEmptyArray(formData.tags)) {
    errors.push('At least one tag is required');
  }

  if (isEmptyArray(formData.categories)) {
    errors.push('At least one category must be selected');
  }

  if (isEmptyArray(formData.items)) {
    errors.push('Items list cannot be empty');
  }

  return errors;
}

Conditional array operations

function safeConcatenate(...arrays: unknown[]): any[] {
  const validArrays = arrays.filter(arr => {
    return Array.isArray(arr) && !isEmptyArray(arr);
  }) as any[][];

  if (validArrays.length === 0) {
    console.warn('No valid non-empty arrays to concatenate');
    return [];
  }

  return validArrays.reduce((result, arr) => result.concat(arr), []);
}

// Usage
console.log(safeConcatenate([1, 2], [], [3, 4], null)); // [1, 2, 3, 4]
console.log(safeConcatenate([], '', {})); // []

API response handling

interface ApiResponse {
  data: unknown;
  message: string;
}

function handleApiResponse(response: ApiResponse) {
  if (isEmptyArray(response.data)) {
    return {
      success: true,
      message: 'No data available',
      items: [],
      count: 0
    };
  }

  if (Array.isArray(response.data)) {
    return {
      success: true,
      message: 'Data loaded successfully',
      items: response.data,
      count: response.data.length
    };
  }

  throw new Error('Expected array data in API response');
}

Playground

import { isEmptyArray } from '@winglet/common-utils';

// True cases - empty arrays
console.log(isEmptyArray([])); // true
console.log(isEmptyArray(new Array())); // true
console.log(isEmptyArray(Array.from(''))); // true

// False cases - not empty arrays
console.log(isEmptyArray([1, 2, 3])); // false (has elements)
console.log(isEmptyArray([undefined])); // false (has one element)
console.log(isEmptyArray([''])); // false (has one empty string element)
console.log(isEmptyArray(null)); // false (not an array)
console.log(isEmptyArray(undefined)); // false (not an array)
console.log(isEmptyArray({})); // false (object, not array)
console.log(isEmptyArray('')); // false (empty string, not array)
console.log(isEmptyArray({ length: 0 })); // false (array-like, not array)

Notes

Validation Logic:

1. First checks if value is an array using isArray()
2. Then validates that length property equals 0
3. Both conditions must be true for positive result

Use Cases:

• Form validation (required array fields)
• API response validation
• Conditional array processing
• Default value assignment
• Array concatenation utilities

Performance:

• Optimized with early return if not an array
• Direct property access for length check
• More efficient than Array.isArray() && array.length === 0

Related Functions:

• Use isArray() for general array detection
• Use isEmptyObject() for empty object detection
• Use isTruthy() for general emptiness checks