throws 'userColors[color].toLowerCase() is not a function'

[andrewwalters]

If my program contains custom properties for Array, then CheckInput() throws a "TypeError: userColors[color].toLowerCase() is not a function" error. This is because for (var color in userColors) iterates over both the array elements and the custom properties. I believe changing for...in to for...of will fix it. To reproduce:

Array.prototype.foo = () => { return 0; };
const cfonts = require('cfonts');
cfonts.say('Hello', { colors: [ 'green' ] });

[dominikwilkowski]

Hi @andrewwalters
Changing the prototype of native objects you don't have ownership over is a big no-no and largely considered an anti pattern because it can effect other code like libraries ironically illustrated by your submitted issue. But I know that some old code bases did this and we don't always have the luxury of rebuilding everything or working with modern code so I had a look and since my code here was a bit old I decided to rewrite the loops from for in to forEach which make much more sense here :)
That will incidentally also fix your issue and is now live with v2.1.3.

Hope it helps