TheAlgorithms/JavaScript · error · Error

Provided input is not an array

Error message

Provided input is not an array

What it means

generateSubSets builds the power set by indexing inputArray[j] for each set bit, so it requires a real Array. The guard uses Array.isArray to reject iterables that are not arrays (Sets, strings, generators) which would break the indexed access.

Source

Thrown at Bit-Manipulation/GenerateSubSets.js:11

/**
 * @function generateSubSets
 * @param {Array} inputArray
 * @returns {Array}
 * @example [1,2] -> [[],[1],[2],[1,2]]
 */

// The time complexity of this algorithm is BigO(2^n) where n is the length of array
function generateSubSets(inputArray) {
  if (!Array.isArray(inputArray)) {
    throw new Error('Provided input is not an array')
  }
  if (inputArray.length > 32) {
    throw new RangeError('Error size should be less than equal to 32')
  }
  let arrayLength = inputArray.length
  let subSets = []
  // loop till (2^n) - 1
  for (let i = 0; i < 1 << arrayLength; i++) {
    let subSet = []
    for (let j = 0; j < arrayLength; j++) {
      // 1 << j it shifts binary digit 1 by j positions and then we perform
      // and by AND operation we are checking whetheer jth bit
      // in i is set to 1 if result is non zero just add into set
      if (i & (1 << j)) {
        subSet.push(inputArray[j])
      }
    }
    subSets.push(subSet)

View on GitHub (pinned to 5c39e87a9a)

Solutions

1. Pass an Array: generateSubSets([1,2,3]).
2. Spread other iterables first: generateSubSets([...mySet]).
3. For characters, split the string: generateSubSets(str.split('')).

Example fix

// before
generateSubSets(new Set([1,2,3]))
// after
generateSubSets([...new Set([1,2,3])])

function subsetsSafe(iter) {
  const arr = Array.isArray(iter) ? iter : Array.from(iter);
  return generateSubSets(arr);
}

/** @param {unknown} x @returns {x is unknown[]} */
const isArray = x => Array.isArray(x);

try { return generateSubSets(input); }
catch (e) {
  if (e instanceof Error && /not an array/.test(e.message) && input != null) {
    return generateSubSets(Array.from(input));
  }
  throw e;
}

When it happens

Trigger: Passing a Set, a string, a Map, an object, null, undefined, a NodeList, or any non-Array iterable.

Common situations: Converting a Set to subsets without [...set], passing a string expecting character subsets, or handing in a library collection object.

Related errors

• Argument not an Integer
• Error size should be less than equal to 32
• Invalid capacity
• Rule must be an integer between the values 0 and 255 (got ${
• Coefficient a, b should be number

AI-assisted analysis of TheAlgorithms/JavaScript@5c39e87a9a (2026-08-13). Data as JSON: /api/errors/2c39938b82329f73. Report an issue: GitHub.