JavaScript: Mutate the original array to filter out the values specified, based on a given iterator function

JavaScript fundamental (ES6 Syntax): Exercise-160 with Solution

Mutate Array with Filter and Iterator

Write a JavaScript program to mutate the original array to filter out the values specified, based on a given iterator function.

• Check if the last argument provided is a function.
• Use Array.prototype.map() to apply the iterator function fn to all array elements.
• Use Array.prototype.filter() and Array.prototype.includes() to pull out the values that are not needed.
• Set Array.prototype.length to mutate the passed in an array by resetting its length to 0.
• Use Array.prototype.push() to re-populate it with only the pulled values.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
// Define a function 'pullBy' that modifies the input array by removing elements based on specified criteria
// It takes a variable number of arguments:
// 1. 'arr': The array from which elements will be pulled
// 2. '...args': Additional arguments which can be either values or arrays of values to be removed
// If the last argument is a function, it will be used to extract the comparison value from elements
const pullBy = (arr, ...args) => {
  // Determine the number of arguments
  const length = args.length;
  // Extract the last argument if it is a function, which will be used for comparison
  let fn = length > 1 ? args[length - 1] : undefined;
  fn = typeof fn == 'function' ? (args.pop(), fn) : undefined;
  // Map the arguments to comparison values using the provided function
  let argState = (Array.isArray(args[0]) ? args[0] : args).map(val => fn(val));
  // Filter the array to exclude elements that match any of the comparison values
  let pulled = arr.filter((v, i) => !argState.includes(fn(v)));
  // Clear the original array and push the remaining elements from the filtered array
  arr.length = 0;
  pulled.forEach(v => arr.push(v));
};

// Define an array 'myArray' containing objects
var myArray = [{ x: 1 }, { x: 2 }, { x: 3 }, { x: 1 }];

// Call 'pullBy' function to remove elements from 'myArray' based on specified criteria
pullBy(myArray, [{ x: 1 }, { x: 3 }], o => o.x);

// Log the modified 'myArray'
console.log(myArray); // Output: [{ x: 2 }]

Output:

[{"x":2}]

Visual Presentation:

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-160-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that mutates the original array by removing elements that satisfy a given iterator function.
• Write a JavaScript function that filters an array in-place using a callback, leaving only the elements that fail the test.
• Write a JavaScript program that applies an iterator to each element and splices out those that return true.
• Write a JavaScript program that modifies an array by iterating over it and removing elements based on a custom condition.

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