Iterator: string

The native string is a built-in iterable object

string is iterable

the strings object key Symbol.iterator` is a function

const s = 'abc'; const isA = typeof s.Symbol.iterator; assert.equal(isA, 'function');

use Array.from() to make an array out of any iterable

const s = 'abc'; const arr = s; assert.deepEqual(arr, ['a', 'b', 'c']);

a string`s iterator

has a special string representation

const s = 'abc'; const iterator = s[Symbol.iterator](); const description = iterator.to____(); assert.equal(description, '[object String Iterator]');

iterator.next() returns an object according to the iterator protocol

const s = 'abc'; const iterator = s[Symbol.iterator](); const value = iterator.___(); assert.deepEqual(value, {done: false, value: 'a'});

the after-last call to iterator.next() says done=true, no more elements

const s = 'abc'; const iterator = s[Symbol.iterator](); iterator.next(); assert.equal(iterator.next().done, true);

Required Knowledge

• basics (Symbol)
• array (Iterator)

Related Katas

Iterator

• array
• string
• protocol

Difficulty Level

TBD

First Published

11 May 2015

Stats

5 tests to solve