Several methods and differences for JavaScript to create empty objects and empty arrays

Here are three ways to create an empty object:

var emptyObj1 = {}; var New Object (); var emptyObj2 = object.create (Object.prototype);

They are the same for JavaScript, and the newly created three objects inherit all the properties and methods of object, so emptyobj1.tostring equals Object.prototype.toString. But be aware that {}.tostring is an error!

Similarly, there are empty array problems:

var emptyArr1 = []; var New Array ();

The above two lines are no different

var arr1 = [' foo ', ' Bar ']; var New Array (' foo ', ' Bar ');

There's no difference between these two lines.

var arr1 = [3];  Arr1.length = = 1, arr1[0] = = 3varnew Array (3); Arr2.length = = 3, arr2[0] = = undefined

The above two lines are different

var arr1 = [];arr1[0] = ' first element '; Console.log (arr1);//["first element"]var C4>new  Array (); arr2[0] = ' first element '; Console.log (ARR2);//["first element"]var ARR3 = object.create (array.prototype); arr3[0] = ' first element 'Console.log (ARR3);//Array {0: "First Element "}

The above code shows that the array created with Object.create returns an object, and if arr3[0] = ' first element ' is replaced with Arr3.push (' first element '), the output will be the same as the above two.

Reference Links:

Http://stackoverflow.com/questions/251402/create-an-empty-object-in-javascript-with-or-new-object

Http://stackoverflow.com/questions/931872/what-s-the-difference-between-array-and-while-declaring-a-javascript-ar

Several methods and differences for JavaScript to create empty objects and empty arrays