SOURCE

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)
console 命令行工具 X clear

                    
>
console