Common methods of Set type in ES6

Common methods of Set

1) The common attribute
size of Set: returns the number of elements in the Set.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)   // Set()括号中传入可迭代对象

// 4.size属性
console.log(arrSet.size);   // 5

2) Common methods of Set
① add(value): Add an element and return the Set object itself.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)  

arrSet.add(100)
console.log(arrSet);    //Set(6) {33,10,25,30,26,100}

② delete(value): Delete the element equal to this value from the set and return the boolean type.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)  

arrSet.delete(30)     // delete方法括号中传入的必须是元素值，不能是索引
console.log(arrSet);    //Set(4) {33,10,25,26}

③ has(value): Determine whether there is an element in the set, and return the boolean type.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)  
console.log(arrSet.has(33));   // true

④ clear(): Clear all the elements in the set, no return value.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)  
arrSet.clear()
console.log(arrSet);    // Set(0) {}

⑤ forEach(callback, [, thisArg]): traverse the set through forEach.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)  
arrSet.forEach(item => {
    
    
    console.log(item);
})

In addition, Set also supports for...of to traverse.

const arr = [33, 10, 25, 30, 33, 26]
const arrSet = new Set(arr)  
for (const item of arrSet) {
    
    
    console.log(item);
}