freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/es6/use-destructuring-assignment-to-assign-variables-from-nested-objects.english.md

id, title, challengeType, isHidden, forumTopicId

id	title	challengeType	isHidden	forumTopicId
587d7b89367417b2b2512b4a	Use Destructuring Assignment to Assign Variables from Nested Objects	1	false	301214

Description

You can use the same principles from the previous two lessons to destructure values from nested objects.

Using an object similar to previous examples:

const user = {
  johnDoe: { 
    age: 34,
    email: 'johnDoe@freeCodeCamp.com'
  }
};

Here's how to extract the values of object properties and assign them to variables with the same name:

const { johnDoe: { age, email }} = user;

And here's how you can assign an object properties' values to variables with different names:

const { johnDoe: { age: userAge, email: userEmail }} = user;

Instructions

Replace the two assignments with an equivalent destructuring assignment. It should still assign the variables lowToday and highToday the values of today.low and today.high from the LOCAL_FORECAST object.

Tests

tests:
  - text: You should remove the ES5 assignment syntax.
    testString: assert(!code.match(/lowToday = LOCAL_FORECAST\.today\.low/g) && !code.match(/highToday = LOCAL_FORECAST\.today.high/g))
  - text: You should use destructuring to create the <code>lowToday</code> variable.
    testString: assert(code.match(/(var|const|let)\s*{\s*today\s*:\s*{\s*(low\s*:\s*lowToday[^}]*|[^,]*,\s*low\s*:\s*lowToday\s*)}\s*}\s*=\s*LOCAL_FORECAST(;|\s+|\/\/)/g));
  - text: You should use destructuring to create the <code>highToday</code> variable.
    testString: assert(code.match(/(var|const|let)\s*{\s*today\s*:\s*{\s*(high\s*:\s*highToday[^}]*|[^,]*,\s*high\s*:\s*highToday\s*)}\s*}\s*=\s*LOCAL_FORECAST(;|\s+|\/\/)/g));
  - text: <code>lowToday</code> should be equal to <code>64</code> and <code>highToday</code> should be equal to <code>77</code>.
    testString: assert(lowToday === 64 && highToday === 77);

Challenge Seed

const LOCAL_FORECAST = {
  yesterday: { low: 61, high: 75 },
  today: { low: 64, high: 77 },
  tomorrow: { low: 68, high: 80 }
};

// Only change code below this line
  
const lowToday = LOCAL_FORECAST.today.low;
const highToday = LOCAL_FORECAST.today.high;

// Only change code above this line

Solution

const LOCAL_FORECAST = {
  yesterday: { low: 61, high: 75 },
  today: { low: 64, high: 77 },
  tomorrow: { low: 68, high: 80 }
};
 
const { today: { low: lowToday, high: highToday }} = LOCAL_FORECAST;