Let yourDoublePieceOfCake = infiniteCake.slice(0,2) // (2) Ĭonsole.log(infiniteCake) //Īs you see, inifinteCake is unmodified. Let myPieceOfCake = infiniteCake.slice(0,1) // If start is -ve, the elements are counted from the end.Ĭonst infiniteCake =.If end is omitted, end becomes the end (last element) of the array.A new array is returned and the original array is unmodified.But unlike slicing a cake, slicing an array does not cut the actual array, but keeps it unmodified (infinite cake!). So I am hoping this trick will help both me and you in the future: S (p) lice = Slice + (p) => Slice + in (p) laceĪ() is used to slice an array from the start point to the end point, excluding the end.Īs the name suggests, it is used to slice elements out of an array. In JavaScript, all standard built-in object-copy operations ( spread syntax, (), (), om(), Object.assign(), and Object.create()) create shallow copies rather than deep copies.This title could have been 'how not to get confused between JavaScript's splice and slice,' because I can never remember the difference between the two. That behavior contrasts with the behavior of a deep copy, in which the source and copy are completely independent.įor shallow copies, it's important to understand that selectively changing the value of a shared property of an existing element in an object is different from assigning a completely new value to an existing element.įor example, if in a shallow copy named copy of an array object, the value of the copy element is, then the corresponding element in the source object will not change - because in that case, you're not just selectively changing a property of an existing array element that the shallow copy shares with the source object instead you're actually assigning a completely new value to that copy array element, just in the shallow copy.

As a result, when you change either the source or the copy, you may also cause the other object to change too - and so, you may end up unintentionally causing changes to the source or copy that you don't expect. A shallow copy of an object is a copy whose properties share the same references (point to the same underlying values) as those of the source object from which the copy was made.

Array slice in javascript