Array (array) object-> unshift () method

1. Definition and usage

　　The unshift () method adds one or more elements to the beginning of the array and returns the new length.

　　grammar:

　　　　array.unshift(item1,item2, ..., itemX)

　　　　Parameters: item1 , item2 , ...,  itemX add one or more elements to the beginning of the array.

　　Note:  This method will change the number of arrays

　　Examples:

var arr = [1,2,3,4,5];
arr.unshift(6,7,8);
console.log(arr);

　　Output: