Discover and allocate personalized entity

Question

Discover and allocate personalized entity

My goal is to locate an item in a list and transfer some of its attributes to another item. The code I currently have feels messy and inefficient.

this.myResult = {value1: null, value2: null};
this.myArray = [
  { a: 'test1', b: 1, c: {subObject1}},
  { a: 'test2', b: 2, c: {subObject2}}
];

let result = this.myArray.find(myObject => myObject.b === 2);

this.myResult = {
   value1: result.a,
   value2: result.b
}

Is there a more elegant way to utilize the result of the Array.find() function in another lambda function and update myResult without the need for a temporary variable? I'm exploring options similar to the following code snippet, and willing to consider the use of libraries like lodash.

this.myResult = {value1: null, value2: null};
this.myArray = [
  { a: 'test1', b: 1, c: {subObject1}},
  { a: 'test2', b: 2, c: {subObject2}}

this.myArray
  .find(myObject => myObject.b === 2)
  .then(result => {
    this.myResult = {
      value1: result.a,
      value2: result.b
    }
  });

EDIT:

After discussions in the comments, I am interested in a solution involving something akin to a .map function following the .find

this.myResult = {value1: null, value2: null};
this.myArray = [
  { a: 'test1', b: 1, c: {subObject1}},
  { a: 'test2', b: 2, c: {subObject2}}

this.myArray
  .find(myObject => myObject.b === 2)
  .map(result => {
    this.myResult = {
      value1: result.a,
      value2: result.b
    }
  });

typescript

Answer 1

Answer №1

Let's delve into the concept you explored in your second code snippet, where you discussed the solution you desire using the .then() method.

The concept of function chaining involves performing sequential operations on a value, especially when working with iterable objects like arrays.

For instance:

[1, 2, 3].map(fn1).toSorted(fn2).with(fn3)

In this scenario, each function within the chain accepts a callback that gets executed for each element in the array. However, the challenge arises when you simply want to pass the result of the previous operation to another function within the same chain.

Similar to your situation:

// Note: `.doOperation()` is akin to your `.then()`. 
// I opt for the former to prevent confusion with promises.
arr.find(fn1).doOperation((val) => ...)

Regrettably, achieving this directly in JavaScript is not feasible. In other programming languages, this concept is known as piping, with a dedicated operator for it to link expressions together seamlessly.

There is currently a proposal at stage 2 for introducing a piping operator: https://github.com/tc39/proposal-pipeline-operator

If this proposal gets approved in the future, you may be able to implement something like this:

let result = arr.find(fn1) |> (foundValue) => {
  return {
    a: foundValue.a,
    b: foundValue.b
  }
}

You may explore using methods like .reduce() or .forEach() to achieve this without the need for a temporary variable, although it might not align exactly with your desired outcome. Alternatively, to eliminate the temporary variable, you can utilize an IIFE as shown below:

let arr = [
  { a: 'test1', b: 1, c: {subObject1}},
  { a: 'test2', b: 2, c: {subObject2}},
  { a: 'test3', b: 3, c: {subObject3}},
];

let res = (({ a, b }) => ({ a, b }))(arr.find(obj => obj.b === 2))

Answer 2

Let's delve into the concept you explored in your second code snippet, where you discussed the solution you desire using the .then() method.

The concept of function chaining involves performing sequential operations on a value, especially when working with iterable objects like arrays.

For instance:

[1, 2, 3].map(fn1).toSorted(fn2).with(fn3)

In this scenario, each function within the chain accepts a callback that gets executed for each element in the array. However, the challenge arises when you simply want to pass the result of the previous operation to another function within the same chain.

Similar to your situation:

// Note: `.doOperation()` is akin to your `.then()`. 
// I opt for the former to prevent confusion with promises.
arr.find(fn1).doOperation((val) => ...)

Regrettably, achieving this directly in JavaScript is not feasible. In other programming languages, this concept is known as piping, with a dedicated operator for it to link expressions together seamlessly.

There is currently a proposal at stage 2 for introducing a piping operator: https://github.com/tc39/proposal-pipeline-operator

If this proposal gets approved in the future, you may be able to implement something like this:

let result = arr.find(fn1) |> (foundValue) => {
  return {
    a: foundValue.a,
    b: foundValue.b
  }
}

You may explore using methods like .reduce() or .forEach() to achieve this without the need for a temporary variable, although it might not align exactly with your desired outcome. Alternatively, to eliminate the temporary variable, you can utilize an IIFE as shown below:

let arr = [
  { a: 'test1', b: 1, c: {subObject1}},
  { a: 'test2', b: 2, c: {subObject2}},
  { a: 'test3', b: 3, c: {subObject3}},
];

let res = (({ a, b }) => ({ a, b }))(arr.find(obj => obj.b === 2))

Answer 3

Answer №2

Do you think this approach would suit your needs? Assuming that there will only be 1 or 0 matching elements in your array.

It involves filtering the array to create a list of matching elements (in this case, either 1 or 0 elements). Then, we will reduce the array to a single value. If filter() results in an empty array, reduce() will return a default value.

this.myArray = [
  { a: 'test1', b: 1, c: {subObject1},
  { a: 'test2', b: 2, c: {subObject2}
];

this.myResult = this.myArray
    .filter(myObject => myObject.b === 2)
    .reduce((res, curr) => {
        return {
            value1: curr.a,
            value2: curr.b
        }
    }, {value1: null, value2: null});

Answer 4

Do you think this approach would suit your needs? Assuming that there will only be 1 or 0 matching elements in your array.

It involves filtering the array to create a list of matching elements (in this case, either 1 or 0 elements). Then, we will reduce the array to a single value. If filter() results in an empty array, reduce() will return a default value.

this.myArray = [
  { a: 'test1', b: 1, c: {subObject1},
  { a: 'test2', b: 2, c: {subObject2}
];

this.myResult = this.myArray
    .filter(myObject => myObject.b === 2)
    .reduce((res, curr) => {
        return {
            value1: curr.a,
            value2: curr.b
        }
    }, {value1: null, value2: null});

Discover and allocate personalized entity

Answer №1

Answer №2

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