Default values of arguments && modernize some code

[asukaminato0721]

Resolves #6721

Changes:

use default values of arguments, fix some missing ...args, use some native apis.

Screenshots of the change:

PR Checklist

• npm run lint passes
• Inline documentation is included / updated
• Unit tests are included / updated

[limzykenneth]

One comment inline and one more thing which is that there are some inconsistency in terms of space before parenthesis after the function key word, ie

function ()

// or

function()

For most of the rest of the code base, the consistent use is not having the space so I tend towards that. @nickmcintyre I can't find specific recommendation for this in the documentation style guide, do you have some thoughts on this?

[nickmcintyre]

@limzykenneth consistency with no space function() seems like the way to go for now. I'd generally recommend against anonymous functions for documentation, but they're fine in source code.

Longer term, both Airbnb and StandardJS suggest space before parentheses for anonymous functions. Maybe we can revisit style guides on the road to 2.0.

[limzykenneth]

I'll do a final review later today to see if private methods will work or not. After that I will merge this.

[limzykenneth]

The new syntax doesn't seem to work with browserify, we'll re-explore this as part of 2.0. I'll merge this for now. Thanks @asukaminato0721

[adonis-jimenez]

Resolves #6721

Changes:

use default values of arguments, fix some missing ...args, use some native apis.

Screenshots of the change:

PR Checklist

• npm run lint passes
• Inline documentation is included / updated
• Unit tests are included / updated