思路:
function findAllOccurrences(arr, target) {
var a=[]
for(var i =0;i<arr.length;i++){
if(arr[i]==target){
a.push(i);
}
}
return a;
}
function findAllOccurrences(arr, target) {
var temp=[];
arr.forEach(function(val,index){
if (val===target)
{
temp.push(index);
}
});
return temp;
}