zloirock/core-js · error · TypeError

Target is not a typed array

Error message

Target is not a typed array

What it means

aTypedArray is core-js's internal spec-op guard used by every typed-array method it polyfills. If the receiver's internal class is not in the typed-array constructors list (Int8Array ... Float64Array, BigInt64Array, etc.), it throws 'TypeError: Target is not a typed array'. This mirrors the spec's ValidateTypedArray / RequireInternalSlot([[TypedArrayName]]) requirement.

Source

Thrown at packages/core-js/internals/array-buffer-view-core.js:80

};

var getTypedArrayConstructor = function (it) {
  var proto = getPrototypeOf(it);
  if (!isObject(proto)) return;
  var state = getInternalState(proto);
  return (state && hasOwn(state, TYPED_ARRAY_CONSTRUCTOR)) ? state[TYPED_ARRAY_CONSTRUCTOR] : getTypedArrayConstructor(proto);
};

var isTypedArray = function (it) {
  if (!isObject(it)) return false;
  var klass = classof(it);
  return hasOwn(TypedArrayConstructorsList, klass)
    || hasOwn(BigIntArrayConstructorsList, klass);
};

var aTypedArray = function (it) {
  if (isTypedArray(it)) return it;
  throw new TypeError('Target is not a typed array');
};

var aTypedArrayConstructor = function (C) {
  if (isCallable(C) && (!setPrototypeOf || isPrototypeOf(TypedArray, C))) return C;
  throw new TypeError(tryToString(C) + ' is not a typed array constructor');
};

var exportTypedArrayMethod = function (KEY, property, forced, options) {
  if (!DESCRIPTORS) return;
  if (forced) for (var ARRAY in TypedArrayConstructorsList) {
    var TypedArrayConstructor = globalThis[ARRAY];
    if (TypedArrayConstructor && hasOwn(TypedArrayConstructor.prototype, KEY)) try {
      delete TypedArrayConstructor.prototype[KEY];
    } catch (error) {
      // old WebKit bug - some methods are non-configurable
      try {
        TypedArrayConstructor.prototype[KEY] = property;
      } catch (error2) { /* empty */ }

View on GitHub (pinned to 84e45fba09)

Solutions

1. Pass a genuine typed array (Int8Array, Uint8Array, Float32Array, BigInt64Array, etc.).
2. If you have a plain array, convert it first: new Float64Array(arr).
3. If you have an ArrayBuffer, create a view: new Uint8Array(buffer).
4. Check the receiver binding: methods must be invoked as arr.method(...), not detached via .call with a wrong this.

Example fix

// before
Uint8Array.prototype.set.call(plainArray, src); // TypeError: Target is not a typed array
// after
new Uint8Array(plainArray).set(src);

function isTypedArray(v){ return ArrayBuffer.isView(v) && !(v instanceof DataView); }
if (!isTypedArray(receiver)) throw new TypeError('receiver must be a typed array');

function isTypedArray(v){ return v instanceof Int8Array || v instanceof Uint8Array || v instanceof Uint8ClampedArray || v instanceof Int16Array || v instanceof Uint16Array || v instanceof Int32Array || v instanceof Uint32Array || v instanceof Float32Array || v instanceof Float64Array || (typeof BigInt64Array !== 'undefined' && v instanceof BigInt64Array) || (typeof BigUint64Array !== 'undefined' && v instanceof BigUint64Array); }

try { typedArrayMethod.call(recv, ...args); } catch (e) { if (/Target is not a typed array/.test(e.message)) { recv = new Uint8Array(recv.buffer || recv); retry(); } else throw e; }

When it happens

Trigger: Calling a typed-array method (e.g. %TypedArray%.prototype.slice/set/subarray/fill) with `this` set to a plain Array, ArrayBuffer, DataView, or non-object via .call/.apply, or calling a polyfilled standalone helper with a non-typed-array argument.

Common situations: Manual this-binding tricks (Array.prototype.slice.call(fakeTypedArray) style code adapted backwards); code that duck-types on .length and passes arrays; mocks in tests that aren't real typed arrays; passing a DataView where a typed array is required.

Related errors

• ArrayBuffer expected
• is not a typed array constructor
• Incorrect invocation
• Incompatible receiver, ${TYPE} required
• Object already initialized

AI-assisted analysis of zloirock/core-js@84e45fba09 (2026-08-30). Data as JSON: /api/errors/9a1fe42984b738dc. Report an issue: GitHub.