Permissions with Bitwise Operators

    /**
     * Using a single integer to represent multiple permissions
     * based on binary values using bitwise operators
     *
     *  & bitwise AND - if both the top and bottom bit are 1, result is 1
     *  | bitwise OR - if either the top and bottom bit or both are 1, result is 1
     *  ^ bitwise XOR - if only one of the bits are 1, result is 1
     * 0101
     * 0100 & =   0100
     *
     * 0100
     * 1110 | = 1110
     *
     * 0101
     * 0001 ^ = 0100
     *
     * 0 - 0000
     * 1 - 0001 x
     * 2 - 0010 x
     * 3 - 0011
     * 4 - 0100 x
     * 5 - 0101
     * 6 - 0110
     * 7 - 0111
     * 8 - 1000 x
     * 9 - 1001
     * 10 - 1010
     */
    
    const READ = 1;     //  0001
    const DRINK = 2;    //  0010
    const SING = 4;     //  0100
    const DELETE = 8;   //  1000
    
    class Person {
      constructor(name, access = 0) {
        this.name = name;
        this.access = access;
      }
      getAll() {
        return {
          [READ]: !!(this.access & READ),
          [DRINK]: !!(this.access & DRINK),
          [SING]: !!(this.access & SING),
          [DELETE]: !!(this.access & DELETE),
        };
      }
      addPerm(perm) {
        this.access = this.access | perm;
      }
      removePerm(perm) {
        if (this.getAll()[perm]) {
          this.access = this.access ^ perm;
        }
      }
    }
    
    let steve = new Person('Steve', 5);
    let joanne = new Person('Joanne');
    joanne.addPerm(DRINK);
    joanne.addPerm(SING);
    joanne.addPerm(DELETE);
    steve.addPerm(SING);
    
    joanne.removePerm(READ);
    steve.removePerm(READ);
    
    console.log(steve.access, steve.getAll());
    console.log(joanne.access, joanne.getAll());
    
    // console.log(steve.getAll()[READ]);
    // console.log(joanne.getAll()[READ]);