2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								---
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								id: 587d7b89367417b2b2512b4b
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								title: Use Destructuring Assignment to Assign Variables from Arrays
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								challengeType: 1
							 
						 
					
						
							
								
									
										
										
										
											2019-08-05 09:17:33 -07:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								forumTopicId: 301213
							 
						 
					
						
							
								
									
										
										
										
											2021-01-13 03:31:00 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								dashedName: use-destructuring-assignment-to-assign-variables-from-arrays
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								---
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								# --description--
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								ES6 makes destructuring arrays as easy as destructuring objects.
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								One key difference between the spread operator and array destructuring is that the spread operator unpacks all contents of an array into a comma-separated list. Consequently, you cannot pick or choose which elements you want to assign to variables.
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								Destructuring an array lets us do exactly that:
							 
						 
					
						
							
								
									
										
										
										
											2019-05-17 06:20:30 -07:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								const [a, b] = [1, 2, 3, 4, 5, 6];
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								console.log(a, b);
							 
						 
					
						
							
								
									
										
										
										
											2019-05-17 06:20:30 -07:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								The console will display the values of `a`  and `b`  as `1, 2` .
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								The variable `a`  is assigned the first value of the array, and `b`  is assigned the second value of the array. We can also access the value at any index in an array with destructuring by using commas to reach the desired index:
							 
						 
					
						
							
								
									
										
										
										
											2019-05-17 06:20:30 -07:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								const [a, b,,, c] = [1, 2, 3, 4, 5, 6];
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								console.log(a, b, c);
							 
						 
					
						
							
								
									
										
										
										
											2019-05-17 06:20:30 -07:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								The console will display the values of `a` , `b` , and `c`  as `1, 2, 5` .
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								# --instructions--
  
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								Use destructuring assignment to swap the values of `a`  and `b`  so that `a`  receives the value stored in `b` , and `b`  receives the value stored in `a` .
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								# --hints--
  
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								The value of `a`  should be `6` , after swapping.
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								assert(a === 6);
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								The value of `b`  should be `8` , after swapping.
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								assert(b === 8);
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2021-03-02 16:12:12 -08:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								You should use array destructuring to swap `a`  and `b` .
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								assert(/\[\s*(\w)\s*,\s*(\w)\s*\]\s*=\s*\[\s*\2\s*,\s*\1\s*\]/g.test(code));
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								# --seed--
  
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								## --seed-contents--
  
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								let a = 8, b = 6;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								// Only change code below this line
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
											2020-11-27 19:02:05 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								# --solutions--
  
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
									
										
										
										
											2019-02-25 12:57:50 -05:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								let a = 8, b = 6;
							 
						 
					
						
							
								
									
										
										
										
											2019-03-25 19:49:34 +05:30 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								[a, b] = [b, a];
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								```