Understanding JavaScript Symbol - A Unique Identifier

In JavaScript, Symbol("Siamak") is a way to create a unique identifier.

Symbols are a special data type in JavaScript. Even if you create two symbols with the same description ("Siamak" in this case), they will always be unique.

Key Points About Symbols

1. Creating a Symbol:

   const mySymbol = Symbol("Siamak");
   console.log(mySymbol); // Outputs: Symbol(Siamak)
   

2. Uniqueness:

   Even if you do this:

   const symbol1 = Symbol("Siamak");
   const symbol2 = Symbol("Siamak");
   console.log(symbol1 === symbol2); // Outputs: false
   

   The two symbols are different, even if they have the same description.

3. Why Use Symbols?

   • Object Properties: Symbols can be used as unique keys for object properties. They avoid naming conflicts because no two symbols are the same.
   • They are useful for creating "hidden" properties that won't conflict with other keys.

Practical Example: Avoiding Key Conflicts

Here's how to use a Symbol to avoid property name conflicts in an object.

// Example with Symbols
const symId = Symbol("id");

const user = {
   name: "Siamak",
   [symId]: 12345 // Symbol is used as a unique property key
};

console.log(user); 
// Outputs: { name: 'Siamak', [Symbol(id)]: 12345 }

// Accessing the Symbol property
console.log(user[symId]); // Outputs: 12345

// Another script cannot accidentally overwrite this property:
user["id"] = 67890; // Regular key
console.log(user.id); // Outputs: 67890 (regular key)
console.log(user[symId]); // Still Outputs: 12345 (symbol key is untouched)

Key Benefits

• Symbols Prevent Key Overlaps: The Symbol key (symId) and the regular string key ("id") don't clash.
• Hidden Properties: Symbols don't show up in regular for...in or Object.keys() loops.

This makes symbols very useful for internal object properties that you want to stay hidden or unique.