JS：判断是否为数组

1. var a=[];
   console.log(a.constructor)  //ƒ Array() { [native code] }

    

2. var a=[];
   console.log(a instanceof Array)   //true

    

3.  

   var a=[];
   var msg = Object.prototype.toString.call(a);
   +function(){
   	if(msg=="[object Array]"){
   		console.log('这是数组')
   	}else{
   		console.log('这不是数组')
   	}
   }();
   
   //这是数组