Question 294060 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – Optimization Challenge- Merging arrays

I’d like to host a challenge,
I’ve made a JavaScript function that is very unoptimized and can be improved in a million ways,
Could you optimize it to the max?

function merge(array1, array2, array3, array4, array5){
  var result = [];
  var arrays = [array1, array2, array3, array4, array5];
  
  for (var i = 0; i < arrays.length; i++) {
    var array = arrays[i];
    for (var j = 0; j < array.length; j++) {
      var item = array[j];
      if (result.indexOf(item) === -1) {
        result.push(item);
      }
    }
  }
  
  return result;
}

const x = ['hi','hello','hey']
const y = ['apple','banana','orange']
const z = ['hie','helloe','heye']
const w = ['applei','bananai','orangei']
const e = ['hio','helloo','heyo']

console.log(merge(x,y,z,w,e));

Good luck optimizing it as best as you can!

I’ll give out a 2 hints:

  1. Instead of multiple parameters, you could turn it into one parameter that supports infinite arrays,

  2. Instead of using function(), there is an another way that uses less memory

Tags:

2

Answers


  1. 0 
    function merge(...arr) {
  const result = new Set();
  arr.forEach((item) => item.forEach((value) => result.add(value)));
  return Array.from(result);
}

const x = ['hi','hello','hey'];
const y = ['apple','banana','orange'];
const z = ['hie','helloe','heye'];
const w = ['applei','bananai','orangei'];
const e = ['hio','helloo','heyo'];
const mergedArr = merge(x, y, z, w, e);

console.log(mergedArr);
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  2. 0

    Rest parameter syntax can be used to allow passing in any number of arrays. Then, we can flatten the parameter to concatenate all the arrays together. Finally, creating a Set from it and converting back to an array with spread syntax removes duplicates.

    const merge = (...arrs) => [...new Set(arrs.flat())];

const x = ['hi','hello','hey']
const y = ['apple','banana','orange']
const z = ['hie','helloe','heye']
const w = ['applei','bananai','orangei']
const e = ['hio','helloo','heyo']

console.log(merge(x, y, z, w, e));
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