Remove duplicates in an array of numbers – Javascript Coding Question

In a given interview, you may be presented with the following problem:

 

The problem:

“Build a function that takes in an array of numbers, and then returns the array without any duplicate elements“

 

Solution:

The easiest way I found to solve this question has been to loop through the array, then push every item on a new array if it has not been added before.

  1. Since we want to loop through the entire array and never break out, we can use Array.forEach:

    array.forEach(item => {
  2. Inside the loop’s testing function, we push the item into the output array if it this item is not in it already.
    if(!output.includes(item))
          output.push(item);

    Easy huh? Indeed, this is one of the simpler questions I’ve come across.

     

Full working example:

 

let removeDuplicates = array => {
  let output = [];

  array.forEach(item => {
    if (!output.includes(item))
      output.push(item);
  });

  document.write(output);
};

removeDuplicates([1, 2, 3, 2, 4, 4]);

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