Function createCallback

MathBox/mathbox-bundle.js:40929–40962

* Produces a callback bound to an optional `thisArg`. If `func` is a property * name the created callback will return the property value for a given element. * If `func` is an object the created callback will return `true` for elements * that contain the equivalent object properties,

(func, thisArg, argCount)

     * // => [{ 'name': 'fred', 'age': 40 }]
     */
    function createCallback(func, thisArg, argCount) {
      var type = typeof func;
      if (func == null || type == 'function') {
        return baseCreateCallback(func, thisArg, argCount);
      }
      // handle "_.pluck" style callback shorthands
      if (type != 'object') {
        return property(func);
      }
      var props = keys(func),
          key = props[0],
          a = func[key];

      // handle "_.where" style callback shorthands
      if (props.length == 1 && a === a && !isObject(a)) {
        // fast path the common case of providing an object with a single
        // property containing a primitive value
        return function(object) {
          var b = object[key];
          return a === b && (a !== 0 || (1 / a == 1 / b));
        };
      }
      return function(object) {
        var length = props.length,
            result = false;

        while (length--) {
          if (!(result = baseIsEqual(object[props[length]], func[props[length]], null, true))) {
            break;
          }
        }
        return result;
      };
    }

    /**
     * Converts the characters `&`, `<`, `>`, `"`, and `'` in `string` to their