const arr = ['a','b','c','d','e','f','a','b','c']
const target = 'a'
// function findAllOccurrences(arr, target) {
// // arr.index(a,1)
// console.log(arr.indexOf(target,0))
// console.log(arr.indexOf(target,1))
// console.log(arr.indexOf(target,7))
// let res = []
// let id = arr.indexOf(target)
// while(id != -1){
// console.log('循环次数')
// res.push(id)
// id = arr.indexOf(target,id+1)
// console.log('看看',arr.indexOf(target,id))
// }
// console.log(res)
// return res
// }
function findAllOccurrences(arr, target) {
let res = []
arr.forEach((item,index)=>{
if(item === target){
res.push(index)
}
})
return res
}
findAllOccurrences(arr, target)