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JavaScript Circular Buffer Utility

The end goal of this project is to implement the entire JavaScript Array.prototype, and some additional utility methods, as a circular buffer.

Note: This is called a circular buffer because of what this library accomplishes, but is implemented as an Array. This may be confusing for Node users, which may want to use a true Buffer.

While the entire Array.prototype API is on the roadmap, it's not all quite here. Below is the currently implemented API.

Usage

It's simple. Just use it like you would use an Array.

new CBuffer(10);      // empty buffer with length of 10
new CBuffer(1,2,3,4); // buffer with length 4
CBuffer(5);           // For those who are really lazy, new is optional

Included are several non-standard niceties. Like if you want to catch when data is overwritten, just assign a function to the overflow variable and it will be called whenever a value is about to be overwritten and it will pass the value as the first argument:

var myBuff = CBuffer(4);
myBuff.overflow = function(data) {
    console.log(data);
};

myBuff.push(1,2,3,4); // nothing shows up yet
myBuff.push(5);       // log: 1

API

Mutator Methods

  • pop - Removes the last element from a circular buffer and returns that element.
  • push - Adds one or more elements to the end of a circular buffer and returns the new size.
  • reverse - Reverses the order of the elements of a circular buffer.
  • rotateLeft - Rotates all elements left 1, or n, times.
  • rotateRight - Rotates all elements right 1, or n, times.
  • shift - Removes the first element from a circular buffer and returns that element.
  • sort - Sorts the elements of a circular buffer. Unlike native sort, the default comparitor sorts by a > b.
  • unshift - Adds one or more elements to the front of a circular buffer and returns the new size.

Accessor Methods

  • indexOf - Returns the first (least) index of an element within the circular buffer equal to the specified value, or -1 if none is found.
  • lastIndexOf - Returns the last (greatest) index of an element within the circular buffer equal to the specified value, or -1 if none is found.
  • sortedIndex - Returns the position some value would be inserted into a sorted circular buffer ranked by an optional comparitor.

Iteration Methods

  • every - Returns true if every element in the circular buffer satisfies the provided testing function.
  • forEach - Calls a function for each element in the circular buffer.
  • some - Returns true if at least one element in the circular buffer satisfies the provided testing function.

Utility Methods

  • empty - Equivalent to setting Array.length = 0.
  • fill - Fill with passed argument. Also supports functions.
  • first - Returns first value in circular buffer.
  • last - Returns last value in circular buffer.
  • get - Get value at specific index.
  • set - Set value as specific index.
  • toArray - Return clean ordered array of buffer.
  • overflow - Set to function and will be called when data is about to be overwritten.
  • slice - Return a slice of the buffer as an array.