Calculates symmetric difference between two arrays of strings. Main purpose is to detect unused CSS classes.

symdiff takes three arrays of strings as arguments:

1. the classes used in CSS
2. the classes used in templates
3. classes to ignore

It outputs an object with the fields css and templates. For instance:

var css = ["grid", "grid-col", "grid-row"],
    html= ["grid"                        ],
    ignr= [        "grid-col"            ];

symdiff(css, html, ignr)
> { css: ["grid-row"], templates: [] }

Apache 2