Generate password with custom character set and length

password-generator.js

// EcmaScript 2015

export default class PasswordGenerator {
  constructor(
    charset = ""
  ) {
    this.charset = charset.toString().split("").sort().reduce((a, b) => {
      if (a.charAt(a.length - 1) === b) {
        return a;
      }
      
      return a + b;
    });
  }
  
  generate(length = 12) {
    let password = "";
    
    for (let i = 0, c = this.charset, l = this.charset.length; i < length; i += 1) {
      password += this.charset.charAt(Math.floor(Math.random() * l));
    }
    
    return password;
  }
}