let str = 'Masteringjs.ioF';
str.slice(0,-1); // Masteringjs.io
str.substring(0, str.length - 1); // Masteringjs.io
str.substr(0, str.length - 1); // Masteringjs.io
str.replace(/.$/, ''); // Masteringjs.io
// For a number, use d$.
let str = 'Masteringjs.io0';
str.replace(/d$/, ''); // Masteringjs.io
// advanced features
let str2 = 'Masteringjs.io0F';
// If the last character is not a number, it will not replace.
str.replace(/d$/, ''); // Masteringjs.io0F;