Remove duplicates from an ArrayList

You can easily remove duplicates from an ArrayList by using a Set or applying a Filter.

function removeDuplicateThroughSet(numberArray: Array<number>): Set<number> {
  return new Set(numberArray)
}
const numberArray = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5]
console.log(removeDuplicateThroughSet(numberArray))        

The function takes an array of numbers as input and returns a filtered array using the?filter?method. The?filter?method iterates through each element in the array, applying a callback function to determine whether to keep or exclude the element.

The callback function takes two arguments: the first argument represents the current element being processed from the input array, while the second represents its index within the array. It then searches for the first occurrence of the current item within the input array and returns its index.

If the index of the first occurrence strictly equals the current element's index, the condition is met. This suggests that the first occurrence of the current element is at its current position, making it unique (not a duplicate) and, therefore included in the new array returned by?filter.

If the condition is not met, it signifies that the element has already appeared before (is a duplicate), and should be excluded or filtered out.

function filterDuplicates(numberArray: Array<number>): Array<number> {
  return numberArray.filter((item, index) => numberArray.indexOf(item) === index)
}
const numberArray = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5]
console.log(filterDuplicates(numberArray))        

function takes a string as input, which represents the sentence to be sorted. splits the input sentence into an array of words using the space character (" ") as the delimiter. The?split?method is a built-in method for strings that creates a new array by separating the string based on the specified delimiter. then the sort method using the callback function sorts the newly created array alphabetically. finally joins the sorted array back into a sentence using the space character (" ") as the separator.

The?sort?method is a function of the?Array?prototype and can be called on any array variable. It accepts an optional?compareFunction?as a parameter, which is a callback function defining the sorting criteria. If no?compareFunction?is provided, the?sort?method performs a lexicographic sort, treating elements as strings and comparing them based on their Unicode character codes. Elements with lower character codes are placed before elements with higher codes. This default sorting works well for strings, but may not be suitable for other data types like numbers or objects.

The?sort?method modifies the original array, sorting it in-place without creating a new array. If you want to preserve the original array, consider creating a copy using methods like?slice?or the spread operator (...) before sorting.

To define a custom sorting order, provide a?compareFunction?as the argument to the?sort?method. The callback function takes two arguments, both elements from the array being sorted:?a?is the first element for comparison and?b?is the second.

function sortSentance(string: string): string {
  const words = string.split(" ");
  words.sort((a, b) => a.toLowerCase().localeCompare(b.toLowerCase()))
  return words.join(" ")
}
        

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