{
    "histroys": [
        {
            "since": "2.1.15",
            "overloads": [
                {
                    "parameters": [
                        {
                            "name": "keySelector",
                            "types": [
                                "function",
                                "string",
                                "symbol",
                                "number"
                            ],
                            "descriptions": [
                                "用于提取每个元素的键的函数"
                            ],
                            "defaultValue": "defaultKeySelector",
                            "declare": {
                                "returns": {
                                    "type": "any"
                                },
                                "parameters": [
                                    {
                                        "name": "element",
                                        "types": [
                                            "any"
                                        ]
                                    },
                                    {
                                        "name": "index",
                                        "types": [
                                            "number"
                                        ]
                                    }
                                ]
                            }
                        },
                        {
                            "name": "elementSelector",
                            "types": [
                                "function",
                                "string",
                                "symbol",
                                "number"
                            ],
                            "descriptions": [
                                "用于将每个源元素映射到组中的元素的函数"
                            ],
                            "defaultValue": "defaultValueSelector",
                            "declare": {
                                "returns": {
                                    "type": "any"
                                },
                                "parameters": [
                                    {
                                        "name": "element",
                                        "types": [
                                            "any"
                                        ]
                                    },
                                    {
                                        "name": "index",
                                        "types": [
                                            "number"
                                        ]
                                    }
                                ]
                            }
                        },
                        {
                            "name": "resultSelector",
                            "types": [
                                "function",
                                "string",
                                "symbol",
                                "number"
                            ],
                            "descriptions": [
                                "用于从每个组中创建结果值的函数"
                            ],
                            "defaultValue": "defaultResultSelector",
                            "declare": {
                                "returns": {
                                    "type": "any"
                                },
                                "parameters": [
                                    {
                                        "name": "key",
                                        "types": [
                                            "any"
                                        ]
                                    },
                                    {
                                        "name": "grouping",
                                        "types": [
                                            "IGrouping"
                                        ]
                                    }
                                ]
                            }
                        },
                        {
                            "name": "comparer",
                            "types": [
                                "function",
                                "string",
                                "symbol",
                                "number"
                            ],
                            "descriptions": [
                                "用于对键进行比较相等比较器"
                            ],
                            "defaultValue": "defaultEqualityComparer",
                            "declare": {
                                "returns": {
                                    "type": "boolean"
                                },
                                "parameters": [
                                    {
                                        "name": "element",
                                        "types": [
                                            "any"
                                        ]
                                    },
                                    {
                                        "name": "other",
                                        "types": [
                                            "any"
                                        ]
                                    }
                                ]
                            }
                        }
                    ],
                    "returns": {
                        "type": "IEnumerable",
                        "descriptions": [
                            "对一组及其键的投影的结果的集合"
                        ]
                    },
                    "description": "根据指定的键选择器函数对序列中的元素进行分组, 并且从每个组及其键中创建结果值. 通过使用指定的比较器对键值进行比较, 并且通过使用指定的函数对每个组的元素进行投影",
                    "remarks": [
                        "此方法通过延迟执行的方式实现"
                    ],
                    "sees": [
                        {
                            "apis": "IEnumerable",
                            "method": "selectMany"
                        },
                        {
                            "apis": "IEnumerable",
                            "method": "groupJoin"
                        },
                        {
                            "apis": "Enumerable.selectors",
                            "property": "key"
                        },
                        {
                            "apis": "Enumerable.selectors",
                            "property": "value"
                        },
                        {
                            "apis": "Enumerable.selectors",
                            "method": "result"
                        },
                        {
                            "apis": "Enumerable.comparers",
                            "property": "equality"
                        },
                        {
                            "href": "https://msdn.microsoft.com/{language}/library/bb535049(v=vs.110).aspx",
                            "title": "Microsoft MSDN"
                        }
                    ]
                }
            ]
        }
    ]
}