Fastest way to move first element to the end of an Array

Solution 1:

Use the shift() and push() functions:

var ary = [8,1,2,3,4,5,6,7];
ary.push(ary.shift());  // results in [1, 2, 3, 4, 5, 6, 7, 8]

Example:

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

console.log("Before: " + ary);

ary.push(ary.shift());  // results in [1, 2, 3, 4, 5, 6, 7, 8] 

console.log("After: " + ary);

Solution 2:

Use shift and push

var a = ["a","b","c"];
var b = a.shift();
a.push(b);

var b = a.shift();
a[a.length] = b;

Edit Based on updated question

What is going to be the fastest? Really depends on content of the array and what browser/version!

Now what are the ways to remove the first index?

shift()
splice()
slice()

Now what are the ways to add to the last index?

push()
array[array.length]
concat() -- not even going to try

Other ways

for loop - make new array [going to be horrible on large arrays]

JSPerf:

http://jsperf.com/test-swapping-of-first-to-last

What is really the fastest?

What is the fastest really depends on what you are doing with the array. If you are just using the first index, it will be fastest just to make your code read an index and not shift the values. If you are using all the indexes, than just loop and through and when you get to the end start back at zero. Basic counters.

Solution 3:

And here is a sweet ES6 version

let arr = [1,2,3,4,5,6]

const [first, ...rest] = arr;
arr = [...rest,first]

Solution 4:

Use splice to get the first element

var first = array.splice(0,1);

Then push to make if the last.

Since the return value of the splice method is an array, you have to say

array.push(first[0]);

Working example here: JSFIDDLE

Solution 5:

Just in case you want to put any element to the end:

var ary = [8,1,2,3,4,5,6,7];
ary.push(ary.splice(position, 1)[0]);

for position just wrap this in a forEach.