![]() ![]() ![]() In this tutorial, you have learned two ways to merge multiple arrays into a single array by using the JavaScript Array concat() method and spread operator. In ES6, you can use spread operator to merge multiple arrays as follows: let odds = Let moreColors = rgb.concat( 'yellow', 'magento') Ĭonsole.log(moreColors) Code language: JavaScript ( javascript ) If you pass values that are not arrays, into the concat() method, the method will appends each value to the end of the result array: let rgb = When you don’t pass any argument into the concat() method, it simply clones the array and returns it: let colors = Ĭonsole.log(rgb) Code language: JavaScript ( javascript ) In this example, we merge the three arrays: upper, lower, and digits. Let alphanumerics = ncat(lower, digits) Code language: JavaScript ( javascript ) The concat() method allows you to merge more than two arrays as shown in the following example: let upper = Output: Code language: JSON / JSON with Comments ( json ) concat(odds, evens) Ĭonsole.log(combined) Code language: JavaScript ( javascript ) merge odds and evens array let combined =. Similarly, you can call the concat() method on an empty array denoted by ( ): let odds = The elements of the second array are appended to the elements of the first array. We call the concat() method of the odds array method to merge elements of the two arrays. In this example, we have two arrays: odds and evens. Output: Result: Odds: Code language: CSS ( css ) merge odds and evens array let combined = ncat(evens) Ĭonsole.log( 'Odds:', odds) Code language: JavaScript ( javascript ) The concat() method returns a new array and doesn’t change the original arrays. A couple of notes on the following approach: For better stability in filtering, rather than using a blacklist (not null), use a whitelist (Array.isArray) to ensure only arrays are combined. To create a new array with a segment removed and/or replaced without mutating the original array, use toSpliced(). To merge two or more arrays, you use the concat() method of an Array object. Essentially you are asking how to filter all non-array inputs and then combine (or concatenate) them together into a new array. The splice() method of Array instances changes the contents of an array by removing or replacing existing elements and/or adding new elements in place. The concat() method and spread syntax in array literals, on the other hand, are non-mutating both approaches create a new array instead.Summary: in this tutorial, you will learn how to use the JavaScript Array concat() method to merge two or more arrays into a single array. Most importantly, you should remember that the push() mutates the target array, modifying it in place. We've seen different approaches to concatenate multiple arrays into a single one: Set can't contain duplicate values, so when we spread the set into the outer new array, we end up with four unique values: array1 // array2 // uniques // #Summary That new array is passed to the Set constructor. We're concatenating array1 and array2 into a new array that contains all six elements. This is useful when you want to concatenate multiple arrays into a single one and remove any duplicate values: const array1 = Ĭonst uniques = )] Your method is as good as any- youd have to splice each member of your second array individually. We can append all elements of array2 to array1 by looping over array2 and calling array1.push() repeatedly: for ( const element of array2) array // Let's assume we have the following two arrays: const array1 = #Appending Elements to an Existing Array with ()įirst up, the good old () method. Using spread syntax in an array literal.Appending elements to a new array with ().Appending elements to an existing array with ().In this post, I want to compare the following common approaches: Some of them mutate the target array others leave all input arrays unchanged and return a new array instead. In JavaScript, there are several different approaches we can take. We can see that, our output contains all the elements of the two arrays that we have taken. ![]() It's a common task to concatenate multiple arrays into a single one. Concatenating Arrays in JavaScript March 31, 2020 ![]()
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