1、arr.find()

arr.find()是 JavaScript 数组的一个方法，用于查找数组中第一个符合条件的元素。

const arr = [2, 4, 6, 8];
const found = arr.find(element => element > 5);
console.log(found); // 6

除了简单的比较之外，我们还可以利用 find()方法构建更复杂的查找条件。例如：

const people = [ 
{ name: '张三', age: 25, gender: 'male' },  
{ name: '李四', age: 30, gender: 'male' }, 
 { name: '王五', age: 28, gender: 'female' }];
const found = people.find(person => person.gender === 'female' && person.age > 25);
console.log(found); // {name: "王五", age: 28, gender: "female"}

2、arr.filter()

arr.filter()是找到所有符合条件的记录并以新数组形式展示。

const numbers = [1, 2, 3, 4, 5];
const evenNumbers = numbers.filter(number => number % 2 === 0); 
console.log(evenNumbers); // [2, 4]

更复杂一点的例如：

const people = [  
  { name: '张三', age: 25, gender: 'male' },  
  { name: '李四', age: 30, gender: 'male' },  
  { name: '王五', age: 28, gender: 'female' }
];
const found = people.filter(person => person.gender === 'female' && person.age > 25);
console.log(found); 
//[{name: "王五", age: 28, gender: "female"},{ name: '王五', age: 28, gender: 'female' }]