The spread operator can be used to clone an array into a new array. This trick can come in handy when working with arrays of primitives. However, it only shallow clones the array, meaning nested non-primitive values will not be cloned.
const arr = [1, 2, 3]; const arr2 = [...arr]; // [1, 2, 3]
Using the spread operator, it’s possible to combine two or more arrays into one. You should think of this trick as cloning two arrays into a new one. Due to that, the shallow cloning limitation mentioned previously applies here, too.
const arr1 = [1, 2, 3]; const arr2 = [4, 5, 6]; const combined = [...arr1, ...arr2]; // [1, 2, 3, 4, 5, 6]
Similarly to previous tricks, it’s possible to spread an array into a new one and add individual elements, too. This can also be combined with merging multiple arrays, if desired.
const arr = [1, 2, 3]; const arr2 = [0, ...arr, 4]; // [0, 1, 2, 3, 4]
Creates an object from an array, using a function to map each value to a key.
Maps the values of an array to an object using a function.
Creates an object from an array, using the specified key and excluding it from each value.