Question

我正在尝试根据某些条件向对象添加2个属性：例如：

var data= [
              { name:"Jan", score:4, scale:4 },
              { name:"Feb",score:8, scale:3 },
              { name: "Mar", score:2, scale:9 },
              { name: "Apr", score:10, scale:1 }
]


 data.map(function(point) {    
  if (some condition) {
   point.m = {
    a: 2
   } 
 }else {
   point.m = {
    a: 10
   }
 }
})
//so result in the data im expecting to add the prop `m` of type object to the array.

data = [
                  { name:"Jan", score:4, scale:4,m:{a:2} },
                  { name:"Feb",score:8, scale:3,m:{a:2} },
                  { name: "Mar", score:2, scale:9,m:{a:10} },
                  { name: "Apr", score:10, scale:1,m:{a:2}  }
   ]

现在在不同的比例上我想为道具m添加另一个字段，我正在做：

point.m = {
 b: 10 // this value is dynamic so could change.
}

所以我期待：

data = [
                      { name:"Jan", score:4, scale:4,m:{a:2, b:10} },
                      { name:"Feb",score:8, scale:3,m:{a:2, b:10} },
                      { name: "Mar", score:2, scale:9,m:{a:10, b:10} },
                      { name: "Apr", score:10, scale:1,m:{a:2, b:10}  }
       ]

但由于某种原因，它只需要将最后一个字段添加到道具中。我得到结果：

 data = [
                          { name:"Jan", score:4, scale:4,m:{ b:10} },
                          { name:"Feb",score:8, scale:3,m:{ b:10} },
                          { name: "Mar", score:2, scale:9,m:{ b:10} },
                          { name: "Apr", score:10, scale:1,m:{b:10}  }
           ]

我在这里缺少什么？

Answer 1

这部分示例：

point.m = {
 b: 10 // this value is dynamic so could change.
}

用新对象替换 point.m。您想要将其与Object.assign合并。

Object.assign(point.m, { b: 10 })

或者，您可以直接将b分配给m

point.m.b = 10

Answer 2

您正在重写该物业。

data.map(function(point) {
  point.m = {};    
  if (some condition) {
    point.m.a = 2;
   } else {
     point.m.a = 10;
   }
  }

  if (some_other_condition) {
    point.m.b = 10;
  }
});

向对象添加多个属性仅显示最后创建的prop

2 个答案: