06-destructuring.md

Destructuring

1. Given this array:

    let arr1 = ['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight'];
   

   Using a single destructuring assignment, assign to three variables, a, b and c so that a contains one, b contains two, and c contains all of the remaining parameters as an array.

2. What does is the value of p3 here?

    let phonetic = ['sierra', 'charlie'];
    let [p1, p2, p3] = phonetic;
   

   How do you think you could default p3 to a suitable value? Try it.

3. Given this array:

    let arr2 = ['one', 'two', ['three', ['four', ['five', 'six', 'seven']], 'eight']];
   

   Create a destructuring pattern to give this result:

    console.log(m, n, o);       // two six eight
   

4. Assume you have this object:

    let stats = {
    	packetForwarded: 5345,
    	redirectSent: 427,
    	forwardCacheHit: 4821,
    	forwardCacheMiss: 524,
    };
   

   1. Use destructuring to assign variables such that:

      console.log(hits);            // 4821
      console.log(misses);          // 524
      

   2. What happens when this line is executed? Why, and how would you fix it?

      { forwardCacheHit: myhits, forwardCacheMiss: mymisses } = stats;
      

5. Can you destructure a string? Try it.

6. These contrived functions connect to a server and extract data from a 'config' object:

   function connectTo(host, port) {
     console.log('Connecting to ' + host + ' on port ' + port);
   }
   
   function initialize(configObj) {
    var host = configObj.host;
    var port = configObj.port;
   
    connectTo(host, port);
   }
   
   initialize({host: 'localhost', port: 8080});
   

   1. Make suitable conversions to these functions by using ES6 syntax.
   2. If host or port are not provided, default them to localhost and 8080 respectively.