JavaScript: Additional Array Prototypes

gistfile1.js

/**
 * Remove value(s) from an array
 *
 * @return {array} Modified array
 */
if (typeof Array.prototype.remove == 'undefined'
 || typeof Array.prototype.remove == null) {
  Array.prototype.remove = function() {
      var what, a = arguments, L = a.length, ax;
      while (L && this.length) {
          what = a[--L];
          while ((ax = this.indexOf(what)) !== -1) {
              this.splice(ax, 1);
          }
      }
      return this;
  };
}

/**
 * Remove one occurence of value(s) from an array
 *
 * @return {array} Modified array
 */
if (typeof Array.prototype.removeOneOccurence == 'undefined'
 || typeof Array.prototype.removeOneOccurence == null) {
  Array.prototype.removeOneOccurence = function() {
    var what, a = arguments, L = a.length, ax;
    while (L && this.length) {
          what = a[--L];
          if ((ax = this.indexOf(what)) !== -1) {
              this.splice(ax, 1);
          }
    }

    return this;
  };
}

/**
 * Count the number of occurences for a specific value in an array
 *
 * @param  {string} value Value
 *
 * @return {integer}      The number of occurences
 */
if (typeof Array.prototype.countOccurrences == 'undefined'
 || typeof Array.prototype.countOccurrences == null) {
  Array.prototype.countOccurrences = function(value) {
    var count = 0;
    for (var i = 0, j = this.length; i < j; i++) {
      if (this[i] == value) {
        count++;
      }
    }

    return count;
  };
}

/**
 * Check if a there is only one value (and its occurences) in an array
 *
 * @param  {string} value Value
 *
 * @return {boolean}       Whether or not the value (and its occurences) is the only one in the array
 */
if (typeof Array.prototype.checkOnly == 'undefined'
 || typeof Array.prototype.checkOnly == null) {
  Array.prototype.checkOnly = function(value) {
    var occurencesCount = 0;
    for (var i = 0, j = this.length; i < j; i++) {
      if (this[i] == value) {
        occurencesCount++;
      }
    }

    if (occurencesCount == this.length) {
      return true;
    } else {
      return false;
    }
  };
}