Iterator.prototype.forEach()

The forEach() method of {{jsxref("Iterator")}} instances is similar to {{jsxref("Array.prototype.forEach()")}}: it executes a provided function once for each element produced by the iterator.

Syntax#

forEach(callbackFn)

Parameters#

• callbackFn
• : A function to execute for each element produced by the iterator. Its return value is discarded. The function is called with the following arguments:
  • element
  • : The current element being processed.
  • index
  • : The index of the current element being processed.

Return value#

{{jsxref("undefined")}}.

Description#

forEach() iterates the iterator and invokes the callbackFn function once for each element. Unlike most other iterator helper methods, it does not work with infinite iterators, because it is not lazy.

Examples#

Using forEach()#

new Set([1, 2, 3]).values().forEach((v) => console.log(v));

// Logs:
// 1
// 2
// 3

This is equivalent to:

for (const v of new Set([1, 2, 3]).values()) {
  console.log(v);
}

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• Polyfill of Iterator.prototype.forEach in core-js
• es-shims polyfill of Iterator.prototype.forEach
• {{jsxref("Iterator")}}
• {{jsxref("Iterator.prototype.find()")}}
• {{jsxref("Iterator.prototype.map()")}}
• {{jsxref("Iterator.prototype.filter()")}}
• {{jsxref("Iterator.prototype.every()")}}
• {{jsxref("Iterator.prototype.some()")}}
• {{jsxref("Array.prototype.forEach()")}}