Destructuring Assignment question

JavaScript
1

Tell us what’s happening:

Ok so… I understand everything (I think) except I don’t understand why:

const {tomorrow : tempOfTomorrow } = avgTemperatures;

is not

const {tomorrow : tempOfTomorrow } = AVG_TEMPERATURES; ?

Where is avgTemperatures even defined in the first place? If the object tomorrow holds the value of 79, under the constant AVG_TEMPERATURES, and you’re trying to assign that to tempOfTomorrow… where does avgTemperatures come from?

Someone else said: "The function takes a parameter.

Instead of using that parameter, you’ve hardcoded in a reference to the object used to test your code works."
…but I don’t understand this.

Your code so far


const AVG_TEMPERATURES = {
  today: 77.5,
  tomorrow: 79
};

function getTempOfTmrw(avgTemperatures) {
  "use strict";
  // change code below this line
  const { tomorrow : tempOfTomorrow } = avgTemperatures; // change this line
  // change code above this line
  return tempOfTomorrow;
}

console.log(getTempOfTmrw(AVG_TEMPERATURES)); // should be 79

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/es6/use-destructuring-assignment-to-assign-variables-from-objects/

2

the const AVG_TEMPERATURES object is being passed through the console.log function into the getTempOfTmrw function which is using it as avgTemperatures

1 Like
3

So anytime a constant passes through a function… it’s converted into a… standard variable format? Or was it declared that way in the line function getTempOfTmrw(avgTemperatures)?

4

avgTemperatures is the parameter of the getTempOfTomrw function.

That parameter is defined when you pass in the AVG_TEMPERATURES variable, which is an object, as an argument to the function.

So inside the function it’s as if avgTemperatures = AVG_TEMPERATURES.

Does this answer your question? I’m reading this as you are trying to understand the relationship between variables, parameters, and arguments?

1 Like
5

yes it does now. That’s 3 or 4 subtle little nuances I was not quite understanding. Thank you so much.

1 Like
6

no its not converted, it was destructed and then assigned tomorrow value to a new variable called tempOfTomorrow and returned it