How to detect whether two arrays have the same items in es6

Detection steps: 1. Convert both arrays to set type, syntax "new Set(arr)"; 2. Get the intersection of two sets, syntax "new Set([...set1].filter (x=>set2.has(x)))", the intersection elements will be included in a set collection and returned; 3. Convert the set collection containing the intersection elements to an array type, the syntax is "Array.from(rse)" ;4. Determine whether the intersection array is an empty array. If so, there are no identical items. Otherwise, there are identical items.

The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.

Detecting whether two arrays have the same items is to detect whether the two arrays intersect.

Detection idea:

• Get the intersection of two arrays
  

• Determine whether the intersection is empty. If it is empty, there are no identical items. If it is not empty, there are identical items.

Implementation steps:

1. Obtain the intersection of two arrays

In es6, you can use the has() method of the set object in conjunction with the filter() of the array to find the intersection of two arrays.

• Set is a new data structure provided by ES6, which is similar to an array, but has no duplicate values. Using this feature, we can convert the array to a Set type for deduplication, and then use the Array.from method to convert it to an array again.

• The Set has() method indicates whether the Set object contains the specified value. Returns true if the specified value exists, false otherwise.

Note: If you want to use the has() method, you need to convert the array to a set collection type first

let a=[1, 2, 3];
let b=[3, 5, 2];
newA = new Set(a);
newB = new Set(b); 
let intersectionSet = new Set([...newA].filter(x => newB.has(x)));
console.log(intersectionSet);

As you can see At this time, the intersection elements are included in a set collection and return

2. Convert the set collection containing the intersection elements into an array type

In es6, you can use The Array.from method converts a collection into an array type

• The Array.from method is used to convert two types of objects into real arrays: array-like objects and array-like objects. Iterable (iterable) objects (including ES6's new data structures Set and Map).

let intersectionSet = Array.from(new Set([...newA].filter(x => newB.has(x))));
console.log(intersectionSet);

3. Determine whether the intersection array is an empty array

• If If it is an empty array, there will be no identical items

• If it is not an empty array, there will be identical items

if(intersectionSet==[]){
	console.log("没有相同项");
}else{
	console.log("有相同项");
}

Complete code example:

let a=[1, 2, 3];
let b=[3, 5, 2];
console.log(a);
console.log(b);
newA = new Set(a);
newB = new Set(b); 
let intersectionSet = Array.from(new Set([...newA].filter(x => newB.has(x))));
console.log("两个数组的交集：");
console.log(intersectionSet);
if(intersectionSet==[]){
	console.log("没有相同项");
}else{
	console.log("有相同项");
}

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