【笔记】Object.values、Object.entries与Object.fromEntries

Object.values()：以数组形式返回给定对象可枚举属性的值，如：[ 值1，值2，值3，值4 ]

举例如下：

	  //对象
      let obj1 = {one:'a',two:'b',three:'c'};
      Object.values(obj1);   // ["a", "b", "c"]

      //键为数字的对象,注意：此时会按照数字键的顺序输出
      let obj2 = {1:'one',3:'tree',2:'two'};
      Object.values(obj2);   // ["one", "two", "tree"]

      //数组
      let obj3 = ['1','2','3'];
      Object.values(obj3);   // ["1", "2", "3"]

      //字符串
      Object.values('abcd');   // ["a", "b", "c", "d"]

Object.values()：以数组形式返回给定对象可枚举属性的 [键:值]，如：[ [键1，值1]，[键2，值2]，[键3，值3]，[键4，值4] ]

Object.fromEntries()：对Object.values()反向操作，将 [ [键1，值1]，[键2，值2]，[键3，值3]，[键4，值4] ] 转为{键1：值1，键2：值2，键3：值3，键4：值4}

举例如下：

      //对象
      let obj1 = {one:'a',two:'b',three:'c'};
      Object.entries(obj1);   // [["one", "a"],["two", "b"],["three", "c"]]
      //Object.fromEntries()对Object.entries()反向操作
      Object.fromEntries([["one", "a"],["two", "b"],["three", "c"]]);   //{one: "a", two: "b", three: "c"}

      //键为数字的对象，注意：此时会按照数字键的顺序输出
      let obj2 = {1:'one',3:'tree',2:'two'};
      Object.entries(obj2);   //[["1", "one"],["2", "two"],["3", "tree"]]
      //Object.fromEntries()对Object.entries()反向操作
      Object.fromEntries([["1", "one"],["2", "two"],["3", "tree"]]);   //{1: "one", 2: "two", 3: "tree"}

      //数组，注意：此时将数组['1','2','3']当作含数字键的对象{0:'1',1:'2','2','3'}
      let obj3 = ['1','2','3'];
      Object.entries(obj3);   // [["0", "1"],["1", "2"],["2", "3"]]
      //Object.fromEntries()对Object.entries()反向操作
      Object.fromEntries([["0", "1"],["1", "2"],["2", "3"]]);   //{0: "1", 1: "2", 2: "3"}

      //字符串，同数组
      Object.entries('abcd');   // [["0", "a"],["1", "b"],["2", "c"],["3", "d"]]
      //Object.fromEntries()对Object.entries()反向操作
      Object.fromEntries([["0", "a"], ["1", "b"], ["2", "c"], ["3", "d"]]);   //{0: "a", 1: "b", 2: "c", 3: "d"}