JSFiddle - React, Tailwind, and code Playground

JavaScript

function range( start, limit ){
        var assoc_array = {};
        var step = 1;
        var DEFAULT_VALUE = "some value";
        step *= limit.charCodeAt(0) - start.charCodeAt(0) > 0 ? 1:-1;
        while( start !== limit ){
            assoc_array[ start ] = DEFAULT_VALUE;
            start = String.fromCharCode(start.charCodeAt(0)+step);
        }
        assoc_array[ limit ] = DEFAULT_VALUE;
        return assoc_array;
    }

console.log( JSON.stringify(range('a','z'),null,'\t'));
console.log( JSON.stringify(range('z','x'),null,'\t'));