Question

我正在使用React的componentDidUpdate生命周期方法。

我正在尝试确定两个数组是否相同。

我的prevState数组如下所示：

prevState.players = [
  {
    name: 'Wayne Rooney',
    age: 31
  }, 
  {
    name: 'Lionel Messi',
    age: 29
  },
  {
    name: 'Robbie Fowler',
    age: 42
  }
];

并且this.state数组看起来像这样：

this.state.players = [
  {
    name: 'Wayne Rooney',
    age: 31
  }, 
  {
    name: 'Lionel Messi',
    age: 29
  },
  {
    name: 'Robbie Fowler',
    age: 42
  }
];

正如您所看到的，如果您展开下面的代码段，它们就不相同：

let playersOne = [{
    name: 'Wayne Rooney',
    age: 31
  },
  {
    name: 'Lionel Messi',
    age: 29
  },
  {
    name: 'Robbie Fowler',
    age: 42
  }
];

let playersTwo = [{
    name: 'Wayne Rooney',
    age: 31
  },
  {
    name: 'Lionel Messi',
    age: 29
  },
  {
    name: 'Robbie Fowler',
    age: 42
  }
];

console.log(playersOne == playersTwo)

这是我的反应生命周期代码。

  componentDidUpdate(prevProps, prevState) {
    if(prevState.players != this.state.players) {
      this.updatePlayers(this.state);
    }
  }

任何人都可以建议确定数组是否相等的最佳方法吗？

Answer 1

JSON.stringify(playersOne) == JSON.stringify(playersTwo)

Answer 2

您可以使用array#every检查两个对象是否具有相同数量的对象，并且每个对象具有相同数量的键和值。

＆＃13;

let playersOne = [{ name: 'Wayne Rooney', age: 31 }, { name: 'Lionel Messi', age: 29 }, { name: 'Robbie Fowler', age: 42 } ],
    playersTwo = [{ name: 'Wayne Rooney', age: 31 }, { name: 'Lionel Messi', age: 29 }, { name: 'Robbie Fowler', age: 42 } ];
 var isSame = playersOne.length === playersTwo.length && playersOne.every((o,i) => Object.keys(o).length === Object.keys(playersTwo[i]).length && Object.keys(o).every(k => o[k] === playersTwo[i][k]));
console.log(isSame);

＆＃13;

Answer 3

您可以使用array.prototype.every：

var players = [
  {
    name: 'Wayne Rooney',
    age: 31
  }, 
  {
    name: 'Lionel Messi',
    age: 29
  },
  {
    name: 'Robbie Fowler',
    age: 42
  }
];

var statePlayers = [
  {
    name: 'Wayne Rooney',
    age: 31
  }, 
  {
    name: 'Lionel Messi',
    age: 29
  },
  {
    name: 'Robbie Fowler',
    age: 42
  }
];

var equals = players.length === statePlayers.length && players.every((e, i) => e.name === statePlayers[i].name && e.age === statePlayers[i].age);

console.log(equals);

Answer 4

使用来自lodash的_.isEqual;
使用JSON.stringify并比较字符串;

检查两个数组是否包含相同的对象 - 反应componentDidUpdate

4 个答案: