JS set

Create set

// SETS - Store unique values of any type
const set1 = new Set();

Add values to set

方法1——set.add()

//Add values to set
set1.add(100);
set1.add('A string');
set1.add({name:'John'});
set1.add(true);
set1.add(100);

方法2——构造时加入[]

const set2 = new Set([1,true,'string']);
console.log(set2);

set.size

//Get count
console.log(set1.size);

set.has（）查看set中是否存在

注意点
只有primitive type才能被查找到；
string, number,boolean等;

//Chech for values
console.log(set1.has(100));  //true
console.log(set1.has(50+50)); //true =100
console.log(set1.has({name:'John'})); //false 即使相同，object还是不同的

console.log({name:'John'}==={name:'John'}); //false //非primitive type 指向不同的内存地址

console.log('John'==='John'); //true

set.delete()

//DELETE from set
set1.delete(100);
console.log(set1);

遍历set——for…of/ forEach

//Iterate through set

//for...of 
for(let t of set1) {console.log(t);}

//forEach Loop
set1.forEach((t)=>console.log(t))

set转为array

//Convert sets to array
const setArr = Array.from(set1);
console.log(setArr);