TYPESCRIPT

symbol typescript

// Symbol is a primitive data type of JavaScript, along with string, number, 
// boolean, null and undefined. Symbols are immutable, and unique.

let sym2 = Symbol("key");
let sym3 = Symbol("key");
sym2 === sym3; // false, symbols are unique

// Just like strings, symbols can be used as keys for object properties.
const sym = Symbol();
let obj = {
  [sym]: "value",
};
console.log(obj[sym]); // "value"

// Symbols can also be combined with computed property declarations to 
// declare object properties and class members.
const getClassNameSymbol = Symbol();
class C {
  [getClassNameSymbol]() {
    return "C";
  }
}
let c = new C();
let className = c[getClassNameSymbol](); // "C"