underscore.string.js

问题 Underscore.string seems to provide nice features for javascript string manipulation. It seems to have all the good points: license : MIT dependencies : none, it is an extension for Underscore.js but it can be used as standalone, without underscore.js weight (minified & gzipped): 4KB community, contributors: 58 contributors on Github history, contributions: since mid 2010 on Github, contributions seem rather stable although pretty quiet since 2014 Except one point for which I am missing info:

问题 I have an array of objects with duplicates and I'm trying to get a unique listing, where uniqueness is defined by a subset of the properties of the object. For example, Current JSON Object: [{"x":6811,"y":15551,"a":"a"}, {"x":6811,"y":15551,"a":"b"}, {"x":6811,"y":15551,"a":"c"}, {"x":6811,"y":15552,"a":"c"}, {"x":6812,"y":15551,"a":"c"}] How to group by two property The last result is [{"x":6811,"y":15551,"a":["a","b","c"]}, {"x":6811,"y":15552,"a":["c"]}, {"x":6812,"y":15551,"a":["c"]}] How