javascript 判断某个数组中是否包含另一个数组

//是否被包含,是返回true,不是返回false
isContained =(a, b)=>{
if(!(a instanceof Array) || !(b instanceof Array)) return false;
if(a.length < b.length) return false;
var aStr = a.toString();
for(var i = 0, len = b.length; i < len; i++){
if(aStr.indexOf(b[i]) == -1) return false;
}
return true;
}

var a = [1,2,3,4,5];
var b = [1,4,3,2];
var c = [1,6];
alert(isContained(a,b));//true
alert(isContained(a,c));//false