基于指定总量填充对象数组amountFilled字段的实现需求

需求说明 #

现有一个包含数量属性的对象数组，每个对象包含amountToFill（待填充值）和amountFilled（已填充值）字段。要求：

• 给定初始总量amount=50，自动将amountFilled填充至amountToFill的数值，同时逐步扣除amount，直至amount为0
• 若amountFilled初始值大于0，计算总量扣除时仅针对还需填充的差值（即amountToFill - amountFilled）

初始数组 #

amountArray = [
  {
    option:'text',
    amountToFill: 5,
    amountFilled:0,
  },
  {
    option:'text1',
    amountToFill: 3,
    amountFilled:1,
  },
  {
    option:'text2',
    amountToFill: 10,
    amountFilled:0,
  },
  {
    option:'text3',
    amountToFill: 4,
    amountFilled:1,
  },
  {
    option:'text4',
    amountToFill: 4,
    amountFilled:1,
  },
  {
    option:'text5',
    amountToFill: 15,
    amountFilled:0,
  },
  {
    option:'text6',
    amountToFill: 5,
    amountFilled:2,
  },
  {
    option:'text7',
    amountToFill:25,
    amountFilled:3,
  },
  {
    option:'text8',
    amountToFill: 15,
    amountFilled:0,
  },
  {
    option:'text9',
    amountToFill: 25,
    amountFilled:0,
  },
  {
    option:'text10',
    amountToFill: 5,
    amountFilled:0,
  }
];

期望结果 #

amountArray1 = [
  {
    option:'text',
    amountToFill: 5,
    amountFilled:5,
    filled: true
  },
  {
    option:'text1',
    amountToFill: 3,
    amountFilled:3,
    filled: true
  },
  {
    option:'text2',
    amountToFill: 10,
    amountFilled:10,
    filled: true
  },
  {
    option:'text3',
    amountToFill: 4,
    amountFilled:4,
    filled: true
  },
  {
    option:'text4',
    amountToFill: 4,
    amountFilled:4,
    filled: true
  },
  {
    option:'text5',
    amountToFill: 15,
    amountFilled:15,
    filled: true
  },
  {
    option:'text6',
    amountToFill: 5,
    amountFilled:5,
    filled: true
  },
  {
    option:'text7',
    amountToFill:25,
    amountFilled:12,  // 此时amount已耗尽为0
    filled: true  
  },
  {
    option:'text8',
    amountToFill: 15,
    amountFilled:0,
    filled: false 
  },
  {
    option:'text9',
    amountToFill: 25,
    amountFilled:0,
    filled: false 
  },
  {
    option:'text10',
    amountToFill: 5,
    amountFilled:0,
    filled: false 
  }
];

实现逻辑 #

1. 维护剩余可分配的amount值，遍历数组每个对象
2. 计算当前对象还需填充的数量：need = amountToFill - amountFilled
3. 剩余amount >= need时：
   • 将amountFilled设为amountToFill
   • 剩余amount扣除need
   • 标记filled: true
4. 剩余amount < need时：
   • 若剩余amount > 0：把剩余量全部分配给当前对象，amount置0，标记filled: true
   • 若剩余amount == 0：保持原amountFilled不变，标记filled: false

示例代码 #

function fillAmounts(originalArray: any[], initialAmount: number) {
  let remainingAmount = initialAmount;
  // 深拷贝原数组，避免修改原数据
  return originalArray.map(item => {
    const newItem = {...item};
    const need = newItem.amountToFill - newItem.amountFilled;
    
    if (remainingAmount <= 0) {
      newItem.filled = false;
      return newItem;
    }

    if (need <= remainingAmount) {
      newItem.amountFilled = newItem.amountToFill;
      remainingAmount -= need;
      newItem.filled = true;
    } else {
      newItem.amountFilled += remainingAmount;
      remainingAmount = 0;
      newItem.filled = true;
    }
    return newItem;
  });
}

// 使用示例
const amountArray = [/* 初始数组内容 */];
const result = fillAmounts(amountArray, 50);
console.log(result);

内容的提问来源于stack exchange，提问作者John w.