The structure assignment of the variable of JS ES6

Variable structure assigns a lot of users

1. Value of exchange variable

Let x = 1= 2= [Y,x]

The above code swaps the values of the variable x and the variable y, so that it is not only concise, easy to read, and semantically clear.

2. Returning multiple values from a function

The function can only return a value, and if you want to return multiple values, you can only say that they are returned in an array or object. Understanding the Deconstruction assignment , it is very convenient to take the value of these values

// returns an array function example () {    return [n/A = example ();
[A,b,c];   [A]

// returns an object function example () {    return  {        foo:1,        bar:2    = example ();
foo;   1
Bar;   2

3. Definition of function parameters

The deconstruction assignment can be conveniently speaking a set of parameters corresponding to the variable name.

// A parameter is a set of sequential values function f ([x, Y, z]) {    console.log (x, y, z);} f ([+)];  The

// parameter is a set of no-order values function func ({x, y, z}) {    console.log (x, y, z);} Func ({z:3,y:2,x:1}); The

4. Extracting JSON data

Deconstructed assignments are especially useful for extracting data from JSON objects

Let Jsondata = {    ID:,    Status:"OK",    data:[123,456]             = Jsondata;console.log (id,status,number);   "OK" (2) [123, 456]

5. Default value of function parameter

、、、

6. Traverse the map structure

Any object that has the iterator interface deployed can use the for ... of loop traversal. The map structure natively supports the iterator interface, and it is very convenient to get the name and key value with the solution assignment of the variable.

var New Map (); Map.set (' first ', ' Hello '); Map.set (' second ', ' World ') ;  for (let [key,value] of map) {    console.log (key,value);}

First Hello
Second World

If you just want to get the key name, or just want to get the key value, you can write this.

// Get Key Name  for (let [key] of map) {    console.log (key);}

First
Second

// Get key value  for (let [, value] of map) {    Console.log (value);}
Hello
World

7, the input module specified method

When loading a module, it is often necessary to specify the input method. The deconstruction assignment makes the input statement very clear.

const {A, b} = require (' Source-map ');

The structure assignment of the variable of JS ES6