Slice () and splice () in JavaScript

Slice () and splice () are the Two methods of the prototype Array object in JavaScript, and because of the similarity of the method names, it is common to remember the roles of the two and make a clear distinction below.

1.slice (start[, end]) :

Takes an element from an array, returns the sub-array that is fetched, and has no effect on the original array . Wherethe start parameter is required to indicate the starting position of the element, the end parameter is optional, which represents the terminating position of the element, but does not contain the array[end] element (which can be understood as the element in the final fetched array has End-start ), if end is empty, the default is Array.lengh. See a few examples:

var numarray = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]numarray.slice (5)//Return [5, 6, 7, 8, 9]numarray.slice (5, 6)//return [5]numarray/ /[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] The original array is unaffected

2.splice (start[, number, item1, item2, ..., itemn]) :

adds /deletes elements to an array , returns the deleted element, and affects the original array . Wherethe start parameter is required to indicate the starting position of the operation, and the number parameter is optional, indicating how many elements to delete,0 for not deleting the element;item1, item2, ..., itemn parameter is optional, indicating the element value to add. See a few examples:

var numarray = [0,1, 2, 3, 4, 5, 6, 7, 8, 9]myarray.splice (9,1)//[9]myarray//[0,, 3, 4, 5, 6, 7, 8]myarray.splice (8, 1, 8, 9, ten)//[8]myarray//[0, 3, 4, 5, 6, 7, 8, 9, 10]myarray.splice (1)//[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]myarray//[ 0]

Add: common operations for arrays in JavaScript:

1. pop () Shift () :

1.1 Pop () deletes the last element of the array and returns the deleted element:

var numarray = [0,1, 2, 3, 4, 5, 6, 7, 8, 9]numarray.pop ()//9numarray//[0,1, 2, 3, 4, 5, 6, 7, 8]

1.2 shift () deletes the first element of the array and returns the element that was deleted:

var numarray = [0,1, 2, 3, 4, 5, 6, 7, 8, 9]numarray.shift ()//0numarray//[1,2, 3, 4, 5, 6, 7, 8, 9]

2. push () unshift () :

2.1 push () adds one or more elements to the end of the array and returns the length of the array after the element is added:

var numarray = [0,1, 2, 3, 4, 5, 6, 7, 8, 9]numarray.push (10,11,)//13numarray = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

2.2 Unshift () adds one or more elements to the beginning of the array and returns the length of the array after the element is added:

var numarray = [0,1, 2, 3, 4, 5, 6, 7, 8, 9]numarray.unshift (10,11,)//13numarray = [10, 11, 12, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

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Slice () and splice () in JavaScript