Removing Duplicates from the Array

Our Problem

Remove Duplicates from an Array

Create a function that takes an array of items, removes all duplicate items and returns a new array in the same sequential order as the old array (minus duplicates).

Testing:

removeDups([1, 0, 1, 0]) ➞ [1, 0]

removeDups([“The”, “big”, “cat”]) ➞ [“The”, “big”, “cat”]

removeDups([“John”, “Taylor”, “John”]) ➞ [“John”, “Taylor”]

Conditions:

• Test sample contain arrays with both strings and numbers.
• Test samples are case sensitive.
• for above assignment, Try to solve it without using Set

Our Solution

Solution 1

Using plain for loop

function getUnique(arr){
var uniqueArr=[];
for(let i=0;i<arr.length;i++){
if(uniqueArr.indexOf(arr[i]) === -1){
uniqueArr.push(arr[i]);
}
}
return uniqueArr;
}

Solution 2

Using .forEach

function removeDups(arr) {
var unique = []
arr.forEach(function(val){
if(unique.indexOf(val) < 0){
unique.push(val);
}
});

return unique;
}

Solution 3

Using .reduce() — Advance Level

arr.reduce((acc, curr) => acc.indexOf(curr)< 0?[…acc,curr] : acc, []);

Solution 4

Using .filter() — Advance Level

arr.filter((curr, index) => arr.indexOf(curr) === index);

References

JavaScript Array Iteration

Array iteration methods operate on every array item. The forEach() method calls a function (a callback function) once…

www.w3schools.com

https://www.w3schools.com/js/js_arrays.asp