Learn how to use JavaScript Symbols

Let’s learn about JavaScript symbols.
Symbols are used to generate unique and universal symbol values .

Explanation and usage of symbols

Symbolis used to generate unique and immutable symbol values.

Symbols Symbolcan be generated by methods. The argument is a description of the symbol, and symbols created separately with the same value are considered different. Symbols can be created without arguments.

Symbol(symbol description);

　SymbolconstYou can make these symbol values ​​immutable by using and .

const MY_SYMBOL = Symbol();

You can also Symboluse to define properties of objects.

const MY_SYMBOL = Symbol();

const obj = {
  [MY_SYMBOL]: 'hello'
};

console.log(obj[MY_SYMBOL]);  // 'hello'

By using symbols, you 
can identify variables just by name without having to assign values ​​like 0, 1, etc !

Use symbols for if conditional branching

SymbolYou can use the if statement to write conditional branching based on the properties defined in .

const MY_SYMBOL = Symbol();

let mySymbol = MY_SYMBOL;

if (mySymbol === MY_SYMBOL) {
  console.log('The specified symbol.');
} else {
  console.log('Not the specified symbol.');
}

Summary of “Learn to use Symbol”

” Learn how to use Symbol ” is summarized below.

Symbolcan be used to generate unique and immutable symbol values.
These symbolic values ​​are often used to define properties of objects because they can be distinguished from other properties.