js判断类型

typeof(1);　　//number
typeof("s");　　//string
typeof(a);　　//undefined
typeof(true);　　//boolean
typeof(a);　　//function
typeof(a);　　//object(对象、null、数组)

console.log([].constructor == Array);
console.log({}.constructor == Object);
console.log("string".constructor == String);
console.log((123).constructor == Number);
console.log(true.constructor == Boolean);

function isArray(object){
    return object && typeof object===‘object‘ &&
            Array == object.constructor;
}

function isArray(object){
    return  object && typeof object===‘object‘ &&    
            typeof object.length===‘number‘ &&  
            typeof object.splice===‘function‘ &&    
             //判断length属性是否是可枚举的 对于数组 将得到false  
            !(object.propertyIsEnumerable(‘length‘));
}

function isArray(o) {
    return Object.prototype.toString.call(o) === ‘[object Array]‘;
}