JS: best way to keep track of unique key/value pairings?

August 11, 2022

I am iterating through objects of font data and want to push or add their postscript name and style as a key/value pair. The postscript name will always be the regular version of the postscript so I need to keep track of the style with it. For example, I want my data structure to look like:

[
   { "Arial-MT", "Bold" },
   { "Arial-MT", "Regular"}
]

While iterating though, if I come across another postscript_name that is Arial-MT and style of either Bold or Regular, I don’t want to add it to my data object. What is the cleanest approach to this?

>Solution :

Use an object containing Sets of strings.

const styles = {
    "Ariel-MT": new Set(["Bold", "Regular"])
};

postscript_data.forEach(([postscript_name, postscript_style]) => {
    if (styles[postscript_name]) {
        styles[postscript_name].add(postscript_style);
    } else {
        style[postscript_name] = new Set([postscript_style])
    }
});