Array function rotate |
var rotateArray = function(a, inc) {
for (var l = a.length, inc = (Math.abs(inc) >= l && (inc %= l), inc < 0 && (inc += l), inc), i, x; inc; inc = (Math.ceil(l / inc) - 1) * inc - l + (l = inc))
for (i = l; i > inc; x = a[--i], a[i] = a[i - inc], a[i - inc] = x);
return a;
};
var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'];
rotateArray(arr, -1);
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Array prototype rotate |
Array.prototype.rotate = (function() {
return function(inc) {
for (var l = this.length, inc = (Math.abs(inc) >= l && (inc %= l), inc < 0 && (inc += l), inc), i, x; inc; inc = (Math.ceil(l / inc) - 1) * inc - l + (l = inc))
for (i = l; i > inc; x = this[--i], this[i] = this[i - inc], this[i - inc] = x);
return this;
};
})();
var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'];
arr.rotate(1);
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Array prototype rotate with unshift/splice |
Array.prototype.rotate = (function() {
var unshift = Array.prototype.unshift,
splice = Array.prototype.splice;
return function(count) {
var len = this.length >>> 0,
count = count >> 0;
unshift.apply(this, splice.call(this, count % len, len));
return this;
};
})();
var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'];
arr.rotate(1);
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Function rotates with a direction and returns an object with current, prior and next values |
function directionalRotate(direction, counter, arr) {
counter = direction ? (counter < arr.length - 1 ? counter + 1 : 0) : (counter > 0 ? counter - 1 : arr.length - 1)
var currentItem = arr[counter]
var priorItem = arr[counter - 1] ? arr[counter - 1] : arr[arr.length - 1]
var nextItem = arr[counter + 1] ? arr[counter + 1] : arr[0]
return {
"counter": counter,
"current": currentItem,
"prior": priorItem,
"next": nextItem
}
}
var direction = true // forward
var counter = 0
var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'];
directionalRotate(direction, counter, arr)
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pending… |
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