Symbols in ECMAScript 6.0

1. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com

2. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
var firstName = Symbol();
var person = {};
person[firstName] = "Eyal";
console.log( person[firstName] ); // "Eyal"

3. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
var firstName = Symbol("first name");
var person = {};
person[firstName] = "Eyal";
console.log("first name" in person); // false
console.log(person[firstName]); // "Eyal"
console.log(firstName); // "Symbol(first name)"
The Symbol function accepts an optional argument
that is the description of the symbol.

4. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
var symbol = Symbol("test symbol");
console.log( typeof symbol ); // "symbol"

5. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
// Option 1:
var firstName = Symbol("first name");
var person = {};
person[firstName] = "Eyal";
// Option 2:
var person = {
[firstName] : "Eyal"
};
// Option 3:
// make the property read only
Object.defineProperty( person, firstName, { writable: false } );

6. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com

7. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com

8. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com

9. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
class Person{
constructor(name){
this.name = name;
}
[Symbol.toStringTag](){
return "Person";
}
toString(){
return this.name;
}
}
var me = new Person("Eyal Vardi");
console.log(me.toString()); // Eyal Vardi
console.log(Object.prototype.toString.call(me)); // Person

10. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
http://www.2ality.com/
Understanding ECMAScript 6
http://ecmascript6.org/
A Few New Things Coming To JavaScript
HARMONY OF DREAMS COME TRUE
Harmony specification_drafts

11. © 2015 Eyal Vardi. All rights reserved. Tel: 054-5-767-300, Email: evardi@gmail.com
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