invert.js

// Let's define how invert should work

// Given an object
// When invert is passed this object
// Then it should swap the keys and values in the object

// E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}

// function invert(obj) {
//   const invertedObj = {};

//   for (const [key, value] of Object.entries(obj)) {
//     invertedObj.key = value;
//   }

//   return invertedObj;
// }

// a) What is the current return value when invert is called with { a : 1 }
// my guess is that it will return { key: 1 } because the code is setting the property "key" on the invertedObj to the value of 1.

// b) What is the current return value when invert is called with { a: 1, b: 2 }
// { key : 2 } because the loop will overwrite the "key" property with the value of 2 after processing the second key-value pair.

// c) What is the target return value when invert is called with {a : 1, b: 2}
// target output: {1: "a", 2: "b"}

// d) What does Object.entries return? Why is it needed in this program?
// Object.entries returns an array of arrays from an object. It's needed to iterate over each property in the object.

// e) Explain why the current return value is different from the target output
// because the current implementation is using key as a literal property name instead of using the value of the variable key with bracket notation.
// f) Fix the implementation of invert (and write tests to prove it's fixed!)
function invert(obj) {
  const invertedObj = {};

  for (const [key, value] of Object.entries(obj)) {
    invertedObj[value] = key;
  }

  return invertedObj;
}

module.exports = invert;