Function cb

public/javascripts/underscore.js:87–92

(value, context, argCount)

  // to each element in a collection, returning the desired result — either
  // identity, an arbitrary callback, a property matcher, or a property accessor.
  var cb = function(value, context, argCount) {
    if (value == null) return _.identity;
    if (_.isFunction(value)) return optimizeCb(value, context, argCount);
    if (_.isObject(value)) return _.matcher(value);
    return _.property(value);
  };
  _.iteratee = function(value, context) {
    return cb(value, context, Infinity);
  };