Remember, the slice method is immutable and the splice method is mutable. Try it Syntax concat() concat(value0) concat(value0, value1) concat(value0, value1, / ,/ valueN) Parameters valueN Optional Arrays and/or values to concatenate into a new array. This method does not change the existing arrays, but instead returns a new array. Hopefully this post has helped you understand the difference between JavaScript array's slice and splice methods and how they work. The concat () method is used to merge two or more arrays. const array = Ĭonsole.log(array) // Conclusion This means that you can set count to 0 with additional parameters to add to the array. Every parameter after the count parameter will be added to the array. You can pass an unlimited number of parameters to the splice method. When you provide both the start and count parameters, it will remove count number of elements, starting at the start index. When you only provide the start parameter, it will remove all elements from that index to the end of the array. The splice method will directly modified the array, essentially adding or removing elements from it using the optional start and count parameters. When you provide both the start and end parameters, it will return the elements between those two indexes. The start parameter can be negative to start at the end of the array. The start parameter is zero-based so the first element is at index 0.
If you provide the start parameter, it will start at that index and go until the end of the array. They're both optional so if you leave both blank, it will return the entire array. The slice method will take an array and return a new array with the elements specified by the optional start and end parameters. The difference between slice and splice is that slice is immutable whereas splice will mutate the array. Join over 14k others.In this post, we'll learn the difference between the JavaScript array methods slice() and splice() and when it's appropriate to use one over the other. Hate the complexity of modern front‑end web development? I send out a short email each weekday on how to build a simpler, more resilient web. 💥 Flash Sale! This week only, get 50% off every JavaScript course and ebook. You can play with all of the code from today’s article on CodePen.Īnd if you’d like to hear Steve Griffith’s soothing voice explain this, you can watch his video on these methods here. Super nerdy, and may not work for you, but that’s how I keep them sorted in my head. You can cut the array up add, remove or replace things and then tape it all back together. If an array were a film reel, the splice() method behaves like physically splicing that reel would. With the slice() method, you’re taking a slice of an array. I use analog references to help me remember the difference between these two. splice ( 2, 1, 'Hermione' ) How to remember: slicing and splicing splice ( 2, 0, 'Dumbledore' ) // This replaces "Dumbledore" with "Hermione" This adds "Dumbledore" at index 2, and removes 0 items at that index
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