js在数组中查找是否存在某一个数值

1.indexOf() -> ES5

const array = ['apple', 'banance', 'orange']

array.indexOf('apple') // 0 存在

array.indexOf('strawBerry') // -1不存在

2.find() -> ES6

const array = ['apple', 'banance', 'orange']
array.find(obj => obj == 'banance') //banance 存在
array.find(obj => obj == 'strawBally') //undefined 不存在

const arrayList = [
　　{name: '张三'}， {name: '李四'}
]
arrayList.find(obj => obj.name == '李四') //{name: '李四'} 存在
arrayList.find(obj => obj.name == '王五') //undefined 不存在

3.findIndex() -> ES6

const array = ['apple', 'banance', 'orange']
array.findIndex(obj => obj == 'banance') //大于0存在
array.findIndex(obj => obj == 'strawBally') //-1 不存在

4.includes()

const array = ['apple', 'banance', 'orange']
array.includes('banance') //true存在
array.includes('strawBally') //false存在

5.filter()

const array = ['apple', 'banance', 'orange']
array.filter(obj => obj == 'orange') //['orange'] 存在
array.filter(obj => obj == 'strawBally') //[] 不存在

const array = [{ name: 'banance' }, { name: 'apple' }]
console.log(array.filter(obj => obj.name === 'apple')) //[{name: 'apple'}] 存在
console.log(array.filter(obj => obj.name === 'strawBally')) //[] 不存在