const num_rep = ["A;1", "B;2", "C;3"];
const string = 'AABAC.';
How to make every "A" become "1", "B" become "2" and "C" become "3"?
>Solution :
here is the simple almost one-liner to replace symbols with another:
const num_rep = ["A;1", "B;2", "C;3"];
const string = 'AABAC.';
let num_rep_map = num_rep.map(a => a.split(';')).reduce((p, c) => {p[c[0]]=c[1]; return p;}, {});
console.log(string.split('').map(a => num_rep_map[a]??a).join(''));