_.invoke() vs. _.each() vs. _.map()

invoke-vs-each-vs-map.md

_.invoke() vs. _.each() vs. _.map(): read http://stackoverflow.com/questions/13193959/difference-between-underscore-js-each-method-and-invoke-method

• _.invoke(list, methodName, *arguments) methodName is string, is function belongs to object object.methodName(...). return result as _.map()
• _.each(list, iteratee, [context]) iteratee is not string (a function name). iteratee is called for each object/item as its parameter iteratee(object). return no result
• _.map(list, iteratee, [context]) like _.each(), apply iteratee for each item iteratee(object), but difference is that return result