ES6 conversion of new data type set and arr set map

var arr=[11,22,33,11]
			var set1=new Set(arr)// Traversal array   Then call the elements of the array s1.add Add to the collection 
			var arr2=Array.from(set1)// Take out all the data in the data container   Then save the return value of the new array 
			console.log(arr2)

use es A new method is introduced to de duplicate the data

And you can see that set either Grammar sugar only uses standard construction grammar , And set It will automatically go heavy  

set1.add(100)
			set1.add(100)
			set1.add(200)
			set1.add("hello")
			set1.add([100])
			set1.add([100])
			console.log(set1)
			set1.forEach(function(el){
				console.log(el)
			})

 

It is not difficult to see that we use add Function to add elements , Although the two arrays are similar, they are not the same reference, so there is no de duplication

// Combine 
			var arr = [10, 20, 30, 10,{}]
			var arr2 = [100, 200,30,10]
			var set1 = new Set([...arr,...arr2])
			console.log(set1)

  Union

var arr = [10, 20, 30, 10,{}]
			var arr2 = [100, 200,30,10]
			var set2 = new Set(arr.filter(function(el) {
				if (arr2.includes(el)) {
					return el
				}
			}))
			console.log(set2)

Find the intersection

It is more difficult to find the intersection Need to use filter Filter and use us includes To check whether it is in the second array

arr-map

The premise is that it must be a two-dimensional array because map The creation parameter of is an array

var arr=[[1,"hello"],[2,"h5"],[3,{name:"karen"}]]
			var m1=new Map(arr)

map-arr

var arr2=Array.from(m1)
			console.log(arr,m1,arr2,arr==arr2,arr[2][1]==arr2[2][1])

arr Array built-in function conversion Although the content is the same when converting But it's still the previous problem Are two arrays Different references But the reference data stored inside is the same reference

arr-set

var arr=[100,200,100,{age:20},{age:20}]
			var s1=new Set(arr)
			console.log(s1,s1.size)

There are two objects with the same content but different references, so they won't be duplicated , But the basic data type is de duplicated

set-arr

var arr2=Array.from(s1)
			console.log(arr,s1,arr2,arr[4]==arr2[3])

The references of the elements inside remain unchanged