Item unchanged

Question

Item unchanged

Seeking help to understand object mutation during a for loop.

I anticipate that console.log(dish) will display the dish object with an updated ingredients property containing an array of shifted ingredients.

However, when I check dish.ingredients, it only displays the ingredients.

Surprisingly, logging dish shows the dish objects without the ingredients.

What could be causing this behavior?

for (let dish of dishArray) {
  dish['ingredients'] = []
  for (let ingredient of ingredientsArray) {
    if (dish._id.equals(ingredient._dishID)) {
      dish['ingredients'].unshift(ingredient)
    }
  }
  console.log(dish['ingredients'])             <------------- 
  console.log(dish)                            <-------------         
}

dishArray contains an array of dish objects fetched from a mongoose query.

javascript express mongoose

Answer 1

Answer №1

To achieve the desired outcome, in JavaScript you can use the `==` operator without requiring any additional information about your code.

let dishArray = [{
  _id: '0'
}, {
  _id: '1'
}];
let ingredientsArray = [{
  _id: '0',
  _dishID: '0'
}, {
  _id: '1',
  _dishID: '1'
}];

for (let dish of dishArray) {
  dish['ingredients'] = [];

  for (let ingredient of ingredientsArray) {
    if (dish._id == ingredient._dishID) {
      dish['ingredients'].unshift(ingredient);
    }
  }

  console.log(dish['ingredients']);
  console.log(dish);
}

Answer 2

To achieve the desired outcome, in JavaScript you can use the `==` operator without requiring any additional information about your code.

let dishArray = [{
  _id: '0'
}, {
  _id: '1'
}];
let ingredientsArray = [{
  _id: '0',
  _dishID: '0'
}, {
  _id: '1',
  _dishID: '1'
}];

for (let dish of dishArray) {
  dish['ingredients'] = [];

  for (let ingredient of ingredientsArray) {
    if (dish._id == ingredient._dishID) {
      dish['ingredients'].unshift(ingredient);
    }
  }

  console.log(dish['ingredients']);
  console.log(dish);
}

Item unchanged

Answer №1

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