How to load custom module js file in magento 2?

Finally, I got the solution for my query. I would like to share it in details as below.

Step 1: Add your module js file under <Vendor>/<Module_Name>/view/<area>/web/js/

e.g. <Vendor>/<Module_Name>/view/<area>/web/js/flexslider.js

Step 2: Create requirejs-config.js file under <Vendor>/<Module_Name>/view/<area>/

e.g. <Vendor>/<Module_Name>/view/<frontend>/requirejs-config.js

Add following code to requirejs-config.js

var config = {
    map: {
        '*': {
            bannerslider: 'VendorName_ModuleName/js/flexslider'
        }
    }
};

Note: you may set your object name as per your choice. In my case I have set as bannerslider and do not add the .js extension to file name in VendorName_ModuleName/js/flexslider

Step 3: Call the function of your module js in .phtml file as following manner.

<script type="text/javascript">
    require(['jquery','bannerslider'],function($){
        $(window).load(function() {
            $('.flexslider-8').flexslider({
                animation: "fade",
                controlNav: "thumbnails",
                slideshowSpeed: 2000,
                minItems: 2,
                maxItems: 4
            });
        });

    });
</script>

Its working fine for me.

Trace : Use Net tab to see requested URL of js file loaded or not.

My way is:

Step 1

Include an extension's base javascript file using layout instructions.

Step 2

Require the extension's other javascript files from the base file with RequireJS:

require(
    [
      'jquery', 
      '{VendorName}_{ModuleName}{path_to_js_file/relative_to/view/web/no_js_at_end}'
     // ex. Magento/Ui/view/base/web/js/grid/sticky/sticky.js
     // became Magento_Ui/js/grid/sticky/stick
    ], 
    function($, someOtherLibrary) {
        // custom code here...
    );
});