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fix: output of the Symbol type #438

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fix: output of the Symbol type #438

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10 changes: 5 additions & 5 deletions manuscript/06-Symbols.md
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ person[firstName] = "Nicholas";

console.log("first name" in person); // false
console.log(person[firstName]); // "Nicholas"
console.log(firstName); // "Symbol(first name)"
console.log(firstName); // Symbol(first name)
```

A symbol's description is stored internally in the `[[Description]]` property. This property is read whenever the symbol's `toString()` method is called either explicitly or implicitly. The `firstName` symbol's `toString()` method is called implictly by `console.log()` in this example, so the description gets printed to the log. It is not otherwise possible to access `[[Description]]` directly from code. I recommended always providing a description to make both reading and debugging symbols easier.
Expand Down Expand Up @@ -91,7 +91,7 @@ let object = {};
object[uid] = "12345";

console.log(object[uid]); // "12345"
console.log(uid); // "Symbol(uid)"
console.log(uid); // Symbol(uid)
```

The `Symbol.for()` method first searches the global symbol registry to see if a symbol with the key `"uid"` exists. If so, the method returns the existing symbol. If no such symbol exists, then a new symbol is created and registered to the global symbol registry using the specified key. The new symbol is then returned. That means subsequent calls to `Symbol.for()` using the same key will return the same symbol, as follows:
Expand All @@ -103,13 +103,13 @@ let object = {
};

console.log(object[uid]); // "12345"
console.log(uid); // "Symbol(uid)"
console.log(uid); // Symbol(uid)

let uid2 = Symbol.for("uid");

console.log(uid === uid2); // true
console.log(object[uid2]); // "12345"
console.log(uid2); // "Symbol(uid)"
console.log(uid2); // Symbol(uid)
```

In this example, `uid` and `uid2` contain the same symbol and so they can be used interchangeably. The first call to `Symbol.for()` creates the symbol, and the second call retrieves the symbol from the global symbol registry.
Expand Down Expand Up @@ -177,7 +177,7 @@ let object = {
let symbols = Object.getOwnPropertySymbols(object);

console.log(symbols.length); // 1
console.log(symbols[0]); // "Symbol(uid)"
console.log(symbols[0]); // Symbol(uid)
console.log(object[symbols[0]]); // "12345"
```

Expand Down