从 onclick 函数为对象赋值

Question

我正在尝试创建一个函数来处理升级的购买。针对特定升级将通过将对象作为参数传递给函数（向上）和升级值（数量）来完成。

这是我的玩家对象：

var player = {
  tech: 0,
  energy: 0,
  upgrades:{
    engi5Perc: 0,
    engi25Perc: 0,
    andro5Perc: 0,
    andro25Perc: 0,
    robot5Perc: 0,
    robot25Perc: 0
  }
}

这是我的功能：

function buyUpgrade(techcost, energycost, up, amount){
  if(techcost <= player.tech && energycost <= player.energy){
    player.tech -= techcost;
    player.energy -= energycost;
    up = amount;
    console.log("Done, upgrade purchased");
  }
}

我的HTML:

<button type="button" onclick="buyUpgrade(1, 1, 'player.upgrades.engi5Perc', 0.005 )">Buy 5%</button>

我的函数中一定存在某种简单的错误，我花了很多时间试图找出它。到目前为止没有运气。

Answer 1

您当前正在将金额分配给字符串 'player.upgrades.engi5Perc'。这行不通。

但是您可以使用方括号来寻址某些对象的属性，其名称您只在运行时知道，例如obj[propertyName] = value.

这里还有一些例子可以说明区别：

var obj = {foo: 'bar'};
var propertyName = 'foo';
// the following two assignments are essentially equal:
obj.foo = 'newBar';
obj[propertyName] = 'newBar';
// while this one is obviously assigning 'newBar' to the wrong property:
obj.propertyName = 'newBar';
// and this is what happens in your function:
'obj.foo' = 'newBar';

试试这个：

function buyUpgrade(techcost, energycost, up, amount){
  if(techcost <= player.tech && energycost <= player.energy){
    player.tech -= techcost;
    player.energy -= energycost;
    player.upgrades[up] = amount;
    console.log("Done, upgrade purchased");
  }
}

并仅使用升级名称调用该函数：

buyUpgrade(1, 1, 'engi5Perc', 0.005 )

从 onclick 函数为对象赋值

Assigning value to object from the onclick function

javascript

function

object

button