JSFiddle - React, Tailwind, and code Playground

JavaScript

function is2dArray(array){
		if(array[0] === undefined){
    	return false;
    }else{
    	return (array[0].constructor === Array);
    }
}
var a =[1,2,3];
var b = [[1,2,3]];

alert(is2dArray(a));
alert(is2dArray(b));