We frequently come across situations where we need to remove duplicate elements from an array while problem-solving. It’s important to have effective techniques to handle the duplicates as they can create ambiguities in certain situations. This article discusses several methods to remove duplicates from JavaScript arrays.<\/p>\n\n\n\n
Removing duplicates means removing the values in the array that have occurred more than once. <\/strong>Let\u2019s say, arr = [1,2,3,4,4,5]. In this, the number four is present twice. We have to reduce this array to [1,2,3,4,5] after removing the duplicates of 4.<\/p>\n\n\n\n This can be done using several methods. Let\u2019s discuss each of them one by one.<\/p>\n\n\n\n The simplest method to remove duplicate elements from an array is using indexOf() method.<\/strong> The indexOf() method is used to find the first index of occurrence of an array element. If the element does not exist in an array, the function simply returns a \u201c-1\u201d instead of returning any index.<\/p>\n\n\n\n We iterate over the elements in the array. We check if the element exists in the resultant array. If it does, we do not push it into the array. If it doesn\u2019t, we push into the resultant array.<\/p>\n\n\n\n Let us see the code of creating an array with no duplicate elements from the array with duplicate elements:<\/p>\n\n\n\n Output:<\/strong><\/p>\n\n\n\n In this method, we first created an empty array called newArray. We iterated over the original array using the for loop. For every element of the original array, we check whether the element is present in the newArray already or not using the indexOf() function. <\/p>\n\n\n\n If the indexOf() function returns a negative one, it means that the element is not present in the newArray. Hence, we add the element into the newArray.<\/p>\n\n\n\n1) Using the indexOf() Method<\/strong><\/h3>\n\n\n\n
\/\/declaring an array\nlet ogArray=[1,2,3,4,4,5]\n\n\/\/create a new array to store unique elements only\nlet newArray=[];\n\n\/\/add unique elements to the newArray\nfor(let i=0;i<ogArray.length;i++) {\n \/\/checking if the element of ogArray exists in the newArray already\n if (newArray.indexOf(ogArray[i]) === -1) {\n \/\/if not, push in the newArray\n newArray.push(ogArray[i]);\n }\n}\n\n\/\/printing the newArray\nconsole.log(newArray);<\/pre><\/div>\n\n\n\n[ 1, 2, 3, 4, 5 ]<\/code><\/pre>\n\n\n\n2) Using the filter() Method<\/strong><\/h3>\n\n\n\n