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

Last update on February 26 2025 11:09:44 (UTC/GMT +8 hours)

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:

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

Flowchart:

Live Demo:

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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