/**
* Combines two or more arrays.
* @param items Additional items to add to the end of array1.
*/
concat(...items: T[][]): T[];
/**
* Combines two or more arrays.
* @param items Additional items to add to the end of array1.
*/
concat(...items: (T | T[])[]): T[];
/**
* 该方法返回指定起始位置的一个新的数组
*/
slice(start?: number, end?: number): T[];
let array: Array<number> = [1, 2, 3];
let array2: Array<number> = [4, 5, 6];
let arrayValue = 7;
array = ( array2);
(array) // [1, 2, 3, 4, 5, 6]
array = (arrayValue);
(array) // [1, 2, 3, 4, 5, 6, 7]
let newArray = (2, 4);
(newArray) // [3, 4]