splice(start, optional delete count, optional items to add)
If nothing was removed from the array, then the return value will just be an empty array. The splice() method is used to add or remove elements of an existing array and the return value will be the removed items from the array. Unlike the slice() method, the splice() method will change the contents of the original array.
Javascript splice array how to#
const newCityArr = cities.slice(5) ĪDVERTISEMENT How to use the splice() JavaScript array method If the start parameter is greater than the last index of the array, then an empty array will be returned. In this example, we will set the start position at -2 which will select the last two cities in the array and return them in a new array. You can also use negative indexes which will start extracting elements from the end of the array. The original array was not modified as we can see here in this example. In this example, we will set the start position at index 2 which will select the last three cities in the array and return them in a new array. It is important to remember that arrays are zero based indexed. You can use the optional start parameter to set a starting position for selecting elements from the array. If you are interested in more useful content related to JavaScript and web development, you can also subscribe to my newsletter.ADVERTISEMENT How to use the slice() JavaScript method using the start parameter That’s why understanding the differences between them is a good thing to do. Of course, they sound similar, but they are completely different in the way they work.
Slice and splice are very useful methods that you must know in JavaScript.
Returns removed elements in a new array. Adds or removes from the original array. It takes one mandatory argument and can take a bunch of optional ones to replace elements. Makes a shallow copy of the original array. Since we removed an element(Alex), the splice method returns that removed element in a new array. In the example above, we removed Alex and added Mehdi and Brad. splice(2,1,"Mehdi","Brad") //returns removed array: console.log(friends) // Original array is mutated. Here is another example where we inserted 2 elements at the 2nd index and removed 1 element: let friends = friends. Since the method splice returns a removed array and we specified 0 elements to remove, the splice method in the example above, returns an empty array. Notice also that the original array is mutated. If I want to transform the splice method above to a literal sentence, I would say at index 0 remove 0 elements and add Mehdi. In the example above, We added Mehdi at the index 0 of the array. splice(0,0,"Mehdi") //returns removed array: console.log(friends) // Original array is mutated. Let’s try some practical examples: let friends = friends. Here is the syntax of the arguments for splice: arr.splice( start, deleteCount, newElem, newElem. For the third argument, you can add more additional arguments if you have a lot of elements to add to the array. The first argument is mandatory and the others are optional. The third parameter specifies the element you want to add(to the array). The second parameter specifies the total number of elements to be removed starting from the start index provided. 
The first parameter (start) specifies the index where an element should be inserted or removed. It returns removed elements in a new array. Unlike slice, the method splice mutates the original array. The method splice() is used to add and remove elements from an array in JavaScript. returns: "Hello I love JavaScript" The splice method returns: 'JavaScript' console.log(str) Does not mutate the original string. slice(-10) // copy elements from the last index to the left 10 indices. slice(2) // slices from index 2 until the end. Here is an example: let str = "Hello I love JavaScript" str. It does not mutate or change the original string. Similar to the array method, the slice method for strings also slices parts of the string and returns it. The method slice() is a string method too. Īs you can see above, the method slice() does not mutate the original array, it only returns a copied array. console.log(languages) // the original array is not mutated. slice(1,3) // languages.slice(2) //(from index 2 until the end of the array). Here is an example: let languages = languages. The second argument is not included, which means when you copy an array from index 1 to index 5, it will only copy from index 1 to index 4. The method slice() takes two arguments: the start index where you will start copying and the end index where the copying ends. It makes a shallow copy of the sliced array and returns the copied array. The method slice in JavaScript is used to copy pieces of an array.
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