How to know the total number elements present in an array?

We can use sizeof() method and length.

For example you can seen below.

    // define an object for sizeof().

    var sofObject =

        {

            'boolean': true,

            'number': 1,

            'array': [1, 2, 3]

        };

    // Get the size of the "sofObject" object.

    var size = sizeof(sofObject);

    //OR

    var object = [];

    var size = object.length;