I made a Node.js colors library in 192 bytes minzipped (+ code explanation!)

let p=['black','red','green','yellow','blue','magenta','cyan','white'],x={},q=['reset','bold','dim','italic','underline','blink',,'reverse','hide','strike'],s=(S='',A=30,T=p)=>T.map((a,i)=>x[a+S]=t=>`\x1b[${i+A}${B}m${t}\x1b[0m`)&&s;s()('Bg',40)('',0,q);export default x;

let p = ['black', 'red', 'green', 'yellow', 'blue', 'magenta', 'cyan', 'white'],
        // colors
        // the colors are positioned to line up with their ansi escape;
        // black is code 30 (0), red is 31 (1), etc.

    q = ['reset', 'bold', 'dim', 'italic', 'underline', 'blink', , 'reverse', 'hide', 'strike'],
        // styles                                              A
        //                                                     |
        // same here; reset is 0, bold is 1, etc               |
        // notice the double comma. It's used to skip items in an array,
        // so we can skip index 6 which has no style associated with it.

    x = {},
        // the final object containing all the functions

    // This function is used to add new colors.
    s = (
        S = '', // a suffix to add to the color's name
        A = 30, // the number to add to each color,
                // for example, black is at index 0. 30 + 0 = 30, which is the escape code for black
        T = p   // the array from which to add colors. The default is p
    ) => T
        .map(   // using map, as it is shorter than `forEach`
                (
                    a, // color
                    i  // index
                ) => x[a + S] = // set the color to...
                        t => `\x1b[${i + A}${B}m${t}\x1b[0m`) // a function which returns colored text...
                        && s; // and return the function itself, so we can chain calls

s()          // call with all the default arguments
 ('Bg', 40)  // call with bg prefix, and add 40 so we get background escape codes
 ('', 0, q); // call with the styles array

export default x; // finally, export our colors