JS把多維數組變成一維數組

var arr=[1,4,[2,3,[6,8],5],7];
	function aa(arr,r){
		var r = r ||[];
		for(var i=0;i<arr.length;i++){
		//console.log(typeof arr[i]);
			if(Object.prototype.toString.call(arr[i])=='[object Array]'){
					aa(arr[i],r);
			}else{
				r.push(arr[i]);
			}
		}
		return r;
	}
	console.log(aa(arr));