JavaScript syntax: Difference between revisions

Revision as of 16:33, 8 April 2021

Revision as of 17:49, 9 April 2021

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</syntaxhighlight>

There are also ''well known symbols''. <!-- TODO: Add table or something -->

<!-- what does this mean and how is it "variable free"?

One of which is <code>Symbol.iterator</code>; if something implements <code>Symbol.iterator</code>, it's iterable:

"The Symbol wrapper also provides access to a [sic] variable free iterator."

<syntaxhighlight lang="javascript">

let x = [1, 2, 3, 4]; // x is an Array and iterable

ex=x[Symbol.iterator]() === Array.prototype[Symbol.iterator]; // providesand anArrays iteratorare for xiterable

while ((exv=ex.next().value)!=undefined) console.log(exv); // displays 1,2,3,4

</syntaxhighlight>

const xIterator = x[Symbol.iterator](); // The [Symbol.iterator] function should provide an iterator for x

-->

xIterator.next(); // { value: 1, done: false }

xIterator.next(); // { value: 2, done: false }

xIterator.next(); // { value: 3, done: false }

xIterator.next(); // { value: 4, done: false }

xIterator.next(); // { value: undefined, done: true }

xIterator.next(); // { value: undefined, done: true }

// for..of loops automatically iterate values

for (const value of x) {

console.log(value); // 1 2 3 4

}

// Sets are also iterable:

[Symbol.iterator] in Set.prototype; // true

for (const value of new Set(['apple', 'orange'])) {

console.log(value); // "apple" "orange"

}

</syntaxhighlight>

==Native objects==