lodash 4.2.1 发布，该版本没有改进记录，但 4.2.0 的改进记录包括：
Added fp/assoc & fp/assocPath as aliases of fp/set
Added fp/dissoc & fp/dissocPath as aliases of fp/unset
Added start param to _.spread
Ensured _.attempt preserves custom errors
Ensured fp/partial & fp/partialRight accept an args param
Ensured fp/unset is immutable
Ensured _.iteratee clones sources for “_.matchesProperty” shorthand
Made _.flatMap a “Collection” method
Removed global references from the npm package
lodash 是一个 JavaScript 实用工具库，提供一致性，模块化，性能和配件等功能。
软件详情：https://github.com/lodash/lodash/releases
来自:开源中国社区
