arraySlice.js

/* 
	Here are few ways to use slice for different use cases. 
	I am just adding few regular usecases I am able to recollect at this point of time. Will add more later.
*/

var arr = [1, 2, 3, 4, 5, 6, 7, 8];

// Traditional use.
arr.slice(0, 2); // result is [1, 2]
arr.slice(0, 3); // result is [1, 2, 3]
arr.slice(0, 8); // result is [1, 2, 3, 4, 5, 6, 7, 8]
arr.slice(0, 9); // result is [1, 2, 3, 4, 5, 6, 7, 8]
// If you observe immediate above line, it's taking second param as length when it exceeds length.

// Now lets use slice for some other purposes.

// Find last item in array
var lastItemInArr = arr.slice(-1).pop(); // result will be 8.
// The above line is equivalant to arr[arr.length-1];

// Lets clone an array
var arrClone = arr.slice(0) // result will be [1, 2, 3, 4, 5, 6, 7, 8];
/* 
	The above line is equivalant to below approaches.
	method 1 :
		var arrClone = [].push.apply([], arr);
	method 2 :
		var arrClone = [];
		for(var i = 0, l = arr.length; i < l; i++){
			arrClone.push(arr[i]);
		}
	
*/

// Lets find last n items in an array
var lastNItems = arr.slice(Math.max(arr.length - n, 1));  @// Thanks to SLaks in SO

// Find first n items in an array
var firstNItems = arr.slice(0, n); // for this requirement Math.min check is not required. Refer above lines to know why.


// And some other experiments
arr.slice(-2) // result will be [7, 8];
arr.slice(-3) // result will be [6, 7, 8];
arr.slice(-7) // result will be [2, 3, 4, 5, 6, 7, 8];
arr.slice(0) // clone of the array as I have mentioned above. I hope you understood how slice(0) works.
arr.slice(-100) // it will also give clone of the array because "100 is greater than the arr length"


// From above lines you may understand that you can use negative values to find last items.