JavaScript: Mutate the original array to filter out the values specified

JavaScript fundamental (ES6 Syntax): Exercise-161 with Solution

Filter and Return Removed Elements

Write a JavaScript program to mutate the original array to filter out the values specified. Returns the removed 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.
• Use Array.prototype.push() to keep track of pulled values.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
// Define a function 'pullAtValue' to remove elements from an array based on specified values
const pullAtValue = (arr, pullArr) => {
  // Initialize an empty array to store removed elements
  let removed = [],
    // Iterate over each element in the array
    // If the element is included in 'pullArr', push it to the 'removed' array; otherwise, keep it
    pushToRemove = arr.forEach((v, i) => (pullArr.includes(v) ? removed.push(v) : v)),
    // Filter the array to remove elements that are included in 'pullArr'
    mutateTo = arr.filter((v, i) => !pullArr.includes(v));
  // Clear the original array
  arr.length = 0;
  // Push the remaining elements from the filtered array back to the original array
  mutateTo.forEach(v => arr.push(v));
  // Return the array of removed elements
  return removed;
};

// Define an array 'myArray' containing elements
let myArray = ['a', 'b', 'c', 'd'];
// Call 'pullAtValue' function to remove elements 'b' and 'd' from 'myArray'
let pulled = pullAtValue(myArray, ['b', 'd']); 
// Log the original data and pulled data


console.log('Original data');
console.log(myArray);// Output: ['a', 'c']
console.log('Pulled data'); 
console.log(pulled);// Output: ['b', 'd']

Output:

"Original data"
["a", "c"]
"Pulled data"
["b", "d"]

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-161-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that removes elements from an array based on a predicate and returns a new array containing the removed elements.
• Write a JavaScript function that splits an array into two arrays: one with elements that satisfy the condition and one with those that do not.
• Write a JavaScript program that uses Array.filter() to separate and then delete matching items, returning the deleted items.
• Write a JavaScript program that mutates an array by extracting elements that pass a test, while returning them in a separate array.

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