Analysis of application examples of ES6 Set structure

This article describes the application of ES6 Set structure. Share it for your reference, as follows:

Set is similar to an array, but the values of members are unique and there are no duplicate values, which implements the iterator interface

The value of set cannot be repeated, the value of the array can be repeated

let arr = [1,2,3,'5','5'];
let st = new Set(arr);
(st); // You can remove duplicate values of the array through set, and the returned pseudo-array(); // 4

set's add , delete, has, clear method

Simple add and delete:

let st = new Set();
var u = {name:'Joh'};
(u);
let bool = (u);
(bool); // true;

Continuous add with has api:

let st = new Set();
var u = {name:'Joh'};
var r = {name:'Lily'};
(u).add(r);
let bool = (r);
(bool); // true
((r)); // false
((u)); // true;

clear clear set collection

let st = new Set();
var u = {name:'Joh'};
var r = {name:'Lily'};
(u).add(r);
();
(); // 0

Convert an array-like model into an array by method

let arr = ['xxx', 'yyyy', 'yyyy'];
let newArr = (new Set(arr));
((newArr)); // true
(newArr); // ["xxx", "yyyy"]

The Set prototype and values are the same value, and can be traversed directly for-of

([] === ); // true
let st = new Set(['xxx', 'yyyy', 'yyyy', 'John']);
for(let k of st) {
 (k); // Output xxx yyy John can directly traverse, compatible with map's data structure}

Keys and values methods in set

let st = new Set(['xxx', 'yyyy', 'yyyy', 'John']);
(); // 3
let itKeys = ();
for(let k of itKeys) {
   (k); // Output xxx yyy John in turn}
('&gt;&gt;&gt;&gt;&gt;');
let itVals = ();
for(let v of itVals) {
   (v); // Output xxx yyy John in turn}

set entries entity object is an array structure of keys and values

let st = new Set(['xxx', 'yyyy', 'yyyy', 'John']);
let entriesIt = (); //
for(let v of entriesIt) {
 (v); // Output ["xxx", "xxx"] ["yyyy", "yyyy"] ["John", "John"]}

About the special nature of NaN in set

let st = new Set();
(NaN === NaN); // false , NaN is incomplete here, so you should be able to add multiple items, not count as duplication, but here is a special example(NaN).add(NaN).add(NaN);
for(let v of st) {
 (v); // Only output one NaN}

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I hope this article will be helpful to everyone's JavaScript programming.