Array.splice(position, 0,new_element_1,new_element_2.) Code language: JavaScript ( javascript ) You can insert one or more elements into an array by passing three or more arguments to the splice() method with the second argument is zero.Ĭonsider the following syntax. Inserting elements using JavaScript Array splice() method The following figure illustrates the scores.splice(0,3) method call above. console.log(deletedScores) // Code language: JavaScript ( javascript ) console.log(scores) // Code language: JavaScript ( javascript )Īnd the deletedScores array contains three elements. The scores array now contains two elements. let deletedScores = scores.splice( 0, 3) Code language: JavaScript ( javascript ) The following statement deletes three elements of the scores array starting from the first element. let scores = Code language: JavaScript ( javascript ) Suppose, you have an array scores that contains five numbers from 1 to 5. Let’s take a look at the following example. The splice() method changes the original array and returns an array that contains the deleted elements. The position specifies the position of the first item to delete and the num argument determines the number of elements to delete. To delete elements in an array, you pass two arguments into the splice() method as follows: Array.splice(position,num) Code language: JavaScript ( javascript ) Deleting elements using JavaScript Array’s splice() method However, you can use this method to delete and replace existing elements as well. JavaScript Array type provides a very powerful splice() method that allows you to insert new elements into the middle of an array. We get even more control of where we place them with the splice() method.Summary: this tutorial shows you how to use the JavaScript Array’s splice() method to delete existing elements, insert new elements, and replace elements in an array. We can add them to the end using their index, the pop() method and the concat() method. We can add them to the beginning with unshift(). In this article, we looked at many ways in JavaScript we can add elements to an array. That right there is the power of slice()! Conclusion In the above example, array.splice(2, 2, 'wednesday') removes two elements from the second position (start) and adds "wednesday" there. We'll be adding "wednesday" in the second position, however we'll also remove erroneous weekend values there: const weekdays = Ĭonst deletedArray = array.splice( 2, 2, 'wednesday') Let's see another example of slice() where we add and delete to the array at the same time. If omitted, it will only remove elements from the array. The optional items to append to the array from start. If omitted, then all the items after start will be deleted. deleteCount - The optional number of items in the array to remove from start.start - The index at which to begin modifying the array.We can concatenate an array with another array: const example1Array1 = Ĭonst example1NewArray = ncat(valuesToAdd) The values being concatenated always come at the end of the array using the method. Unlike the previous methods, it returns a new array. It creates a new copy of the output and does not affect the original arrays. Merging or joining of two or more arrays is achieved by an array's concat() method. Running the above code will display this: 7 Just like unshift(), it also returns the new length of the array: const pushArray = Ĭonst newLength = pushArray.push( 4, 5, 6, 7) The push() method of an array appends one or more elements to the end of it. Finally, at that position, we insert the value of 4. There is no 3rd element, so we're greeted with undefined. The array is 3 in length, and the 2nd element is 3. So, we can directly add the element at the last+1 index. Say, the length of an array is 5, then the last index at which the value will be 4. To add an element to the end of an array, we can use the fact that the length of an array is always one less than the index. When executed, it also returns the new length of an array: const startArray = Ĭonst newLength = startArray.unshift( 2) Īdding Elements to the End of an Array Using the Last Index of the Array The unshift() method in array objects adds one or more elements to the start of an array. Let's get started by adding elements to the beginning of an array! Adding Elements to the Start of an Array
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